Writing a thesis in English is a challenging task—even for native speakers. But for students working in English as a second language, the difficulty level rises even higher. You’re expected to produce polished, academic writing that demonstrates clarity, precision, and subject-matter expertise—often while juggling grammar rules, unfamiliar phrases, and academic vocabulary.
That’s where having the right resources makes all the difference.
As an ESL student, it’s not just about looking up definitions—it’s about understanding how words are used in real academic contexts, learning which phrases sound natural in English, and avoiding common language pitfalls that can weaken your work. A standard dictionary won’t always do the job. You need tools designed specifically for learners and academic writers.
In this guide, we’ve compiled the best dictionaries, phrasebanks, writing tools, and vocabulary resources to help you improve your academic English, build your confidence, and produce a stronger thesis. Whether you need to clarify the difference between “affect” and “effect,” find natural collocations, or discover better ways to structure your argument, you’ll find something here to support your writing journey.
Related: Common ESL Writing Mistakes in Academic Work
Also see: Thesis Proofreading Services for ESL Writers
Best Online Dictionaries for ESL Students
When English isn’t your first language, even a single word can become a roadblock in your academic writing. That’s why using learner-friendly dictionaries—built with non-native speakers in mind—is essential. These resources don’t just give definitions; they explain meaning, show how words are used in context, and often include grammar tips, pronunciation, and usage examples tailored for ESL users.
Here are some of the best online dictionaries to use while writing your thesis:
Oxford Learner’s Dictionaries
Visit: https://www.oxfordlearnersdictionaries.com
This is one of the most trusted resources for ESL learners. It includes simple definitions, British and American variants, example sentences, pronunciation, grammar notes, and even word origin information. The “Oxford 3000” and “5000” lists highlight the most useful academic vocabulary.
Cambridge Dictionary
Visit: https://dictionary.cambridge.org
Another reliable choice for ESL users, the Cambridge Dictionary provides definitions geared toward learners and includes clear examples of how words are used in everyday and academic contexts. It also explains common collocations and helps distinguish British from American usage.
Longman Dictionary of Contemporary English
Visit: https://www.ldoceonline.com
Longman’s learner dictionary is designed for those writing in English academically. It highlights word frequency, usage examples, grammar patterns, and typical errors. It’s also great for improving academic collocations—ideal for ESL students writing theses.
Collins COBUILD Advanced Learner’s Dictionary
Visit: https://www.collinsdictionary.com
Unlike traditional dictionaries that define words in short phrases, COBUILD defines terms in full sentences, making it easier to understand how words are naturally used. It also includes helpful tips on grammar and style.
⚠️ Avoid general translation apps like Google Translate for writing your thesis. While they may be useful for rough translations, they often miss context and produce awkward or incorrect academic phrasing.
Academic English Dictionaries and Phrasebanks
When writing a thesis, understanding everyday English is only half the challenge—you also need to grasp the formal, structured, and often discipline-specific language of academia. That’s where academic dictionaries and phrasebanks come in. These tools help you sound more professional, vary your vocabulary, and write with the precision expected at the university level.
Oxford Collocations Dictionary
Visit: https://www.oxfordlearnersdictionaries.com/word-of-the-day/collocations
Collocations are word combinations that frequently appear together in natural English, such as “draw a conclusion” or “strong evidence.” ESL writers often struggle with unnatural pairings. This resource shows common verb-noun and adjective-noun combinations, helping your writing sound more fluent and academic.
Academic Phrasebank (University of Manchester)
Visit: http://www.phrasebank.manchester.ac.uk
The Academic Phrasebank is a goldmine for anyone unsure how to phrase common elements of academic writing. Whether you’re introducing your research, comparing literature, describing results, or drawing conclusions, this tool offers ready-made examples of language structures used by successful thesis writers.
Macmillan Dictionary
Visit: https://www.macmillandictionary.com
Macmillan provides clearly written definitions and examples, but what makes it particularly useful is its focus on high-frequency academic vocabulary and phrasal verbs. It also includes sound clips for pronunciation and word family breakdowns.
Using tools like these can dramatically improve your academic style and reduce time spent trying to figure out how to phrase complex ideas. They’re especially helpful when writing introductions, literature reviews, and discussions—where tone and structure matter most.
Related: What Is Signposting Language?
Corpus-Based Resources
A corpus is a large, structured collection of texts—often drawn from real academic writing or professional communication. Corpus-based resources are especially useful for ESL thesis writers because they let you see how words and phrases are actually used in context. Instead of guessing whether a sentence sounds right, you can check how native speakers have used similar terms in real-life publications.
Linguee
Visit: https://www.linguee.com
Linguee combines a dictionary with a translation search engine, allowing you to view words in bilingual context. What sets it apart is that it shows real sentences from professional and academic texts, often drawn from scientific reports, legal documents, and journal articles. This makes it easier to see how technical terms are used correctly across languages.
Reverso Context
Visit: https://context.reverso.net
Similar to Linguee, Reverso Context lets you search for a word or phrase and see it used in thousands of authentic examples. It’s especially useful for comparing subtle differences between near-synonyms and for spotting collocations. For ESL students, this helps clarify whether your phrasing is correct in a given academic context.
British Academic Written English (BAWE) Corpus
Visit: https://www.corpus.bham.ac.uk/bawe/
This specialised corpus contains academic texts written by UK university students across a wide range of disciplines. It’s useful if you want to study model writing from real student theses or research papers. While not as intuitive as Linguee or Reverso, it’s a valuable resource for advanced ESL writers aiming to fine-tune their tone and structure.
Tip: Don’t just copy phrases—study sentence structure, tone, and word positioning. The goal is to internalise how English works, not to memorise fixed templates.
Related: How to Avoid Literal Translations
Grammar and Usage Resources
Even if you’ve built a strong vocabulary, mastering English grammar is essential for writing a clear and convincing thesis. For ESL writers, common issues include article use, prepositions, verb tenses, and word order—all of which can affect the clarity and professionalism of your academic work. Fortunately, there are a number of grammar and style resources designed to help.
Purdue OWL (Online Writing Lab)
The Purdue OWL is a free, comprehensive writing resource from Purdue University. It offers in-depth guides on grammar, punctuation, academic tone, and citation styles (APA, MLA, Chicago, etc.). It’s a go-to site for anyone needing help with sentence structure, tenses, or transitioning into academic English.
Grammarly (Free and Premium)
Visit: https://www.grammarly.com
Grammarly can identify basic grammatical errors, awkward phrasing, and inconsistent tone. It’s useful for ESL students working on first drafts—but be cautious. While Grammarly is good at spotting surface-level issues, it may over-correct or misunderstand more complex academic structures. Use it as a helper, not a substitute for learning grammar rules or receiving expert feedback.
Vappingo’s Thesis Proofreading Services
Visit: https://www.vappingo.com/Proofreading-Services/Thesis-Proofreading-Services
Unlike automated tools, Vappingo pairs ESL thesis writers with professional human editors who understand academic expectations and the specific language challenges non-native speakers face. We go beyond checking grammar—we help you improve clarity, tone, structure, and argumentation while maintaining your unique voice.
If you’re unsure about sentence flow, verb usage, or academic tone, our editors will ensure your thesis is error-free and professionally written—ready for submission or publication.
Related: Thesis proofreading for ESL students
Tools for Academic Vocabulary Development
Academic writing isn’t just about correct grammar—it’s also about using the right words to express complex ideas with clarity and precision. For ESL thesis writers, building a strong academic vocabulary is essential. The right tools can help you learn high-frequency academic terms, avoid repetition, and use more natural phrasing.
Academic Word List (AWL)
Visit: https://www.wgtn.ac.nz/lals/resources/academicwordlist
The AWL is a carefully researched list of academic vocabulary commonly found in scholarly articles and essays across disciplines. Words like “evaluate,” “derive,” and “factor” appear frequently in academic writing but less often in general English. Learning these words (and how to use them) can help make your thesis sound more formal and scholarly.
Vocabulary.com
Visit: https://www.vocabulary.com
This site offers an adaptive and gamified way to expand your vocabulary. While it’s not designed specifically for academic English, it allows you to create your own vocabulary lists (e.g., academic verbs or discipline-specific terms) and track your learning over time. It’s especially helpful for memorising definitions and testing your understanding through fun, interactive quizzes.
Quizlet (Custom Flashcards)
Visit: https://www.quizlet.com
Quizlet lets you create and review flashcards for academic vocabulary—perfect for thesis-specific terms you encounter during your reading. Many ESL students use it to build discipline-specific term banks based on their research area (e.g., psychology, engineering, sociology).
Tip: Don’t just memorise word meanings—learn how words function in sentences. Use your new vocabulary in writing exercises and academic summaries to strengthen retention.
Related: Types of Academic Sources
Conclusion and Recommendations
Writing a thesis in a second language is a major achievement—and a serious challenge. But with the right tools at your side, you can overcome common language barriers and communicate your ideas clearly, accurately, and professionally. From learner-friendly dictionaries to powerful academic phrasebanks and grammar checkers, today’s resources offer ESL students real, practical support.
Whether you’re looking up the right preposition, refining your vocabulary, or trying to sound more “academic,” the tools shared in this article can help you:
- Avoid common errors in grammar and usage
- Build a stronger, more formal academic tone
- Learn natural collocations and fixed expressions
- Improve fluency and reader understanding
- Feel more confident in your writing process
But don’t forget: even with great resources, your thesis will benefit from a final professional review. Our Thesis Proofreading Services are specifically designed for ESL students. At Vappingo, we help ensure that your writing is not only correct, but powerful—without losing your unique voice.