Lexio is a free Chrome extension that puts a contextual dictionary one click away on every page. Highlight a word, choose Define with Lexio, and get the meaning that fits this exact sentence — not a generic dictionary entry. Works on web pages, on PDFs opened in Chrome, on Substack, Medium, JSTOR, and the long tail of personal blogs.
No setup, no account, no configuration. Install once and the dictionary is everywhere you read.
Click Add to Chrome on the Web Store listing. The extension requests minimal permissions — only the active tab when you trigger a lookup. No background tracking, no telemetry on what you read.
News article, novel on the Internet Archive, academic paper, contract, foreign-language Wikipedia, PDF you dragged into Chrome — all of them work. The extension doesn't care what kind of page you're on.
Highlight a word or short phrase, right-click, choose Define with Lexio. The popup appears inline with the contextual definition, etymology, and a note on why the author used this exact word rather than its near-synonyms.
If Chrome can render it, Lexio can read it. A non-exhaustive list of places people have used it well:
The Atlantic, The New York Times, The London Review of Books, The Economist, The Guardian, FT.
Substack, Medium, personal blogs, n+1, The Paris Review, The New Yorker.
JSTOR, Project Muse, arXiv, university open-access PDFs, Google Scholar full-text views.
The Internet Archive's borrowable books, Project Gutenberg, Standard Ebooks, Google Books snippets.
Drag any PDF into Chrome and treat it like a page. Selectable text only — image-only scans need OCR (use Lexio's phone camera mode instead).
Le Monde, Frankfurter Allgemeine, El País, Asahi Shimbun, Lenta.ru. Lexio handles 11 reading languages and returns definitions in any of them.
The honest reason most people stop reading difficult prose on the web is friction. You hit a word you don't know. To look it up properly, you have to switch tabs, type the word into Google, scan a list of definitions, decide which one the author probably meant, and switch back. By the time you're back at the sentence, you've lost the thread. Do this ten times in an article and you've forgotten what the article was about.
A Chrome extension solves the friction at the layer where it actually lives: inside the page you're already on. No tab switching, no copy-paste, no guessing which definition fits. Lexio reads the surrounding sentence the same way you do, and gives you the one meaning the author intended — plus a short note on why that word and not its near-synonyms. Total time from problem to solution: under two seconds.
The contextual part matters more than people expect. A regular dictionary will tell you that register means a wide variety of things — a book of records, a vocal range, a level of formality, an electromechanical device for shop transactions. Reading a literary critic, the relevant sense is "level of formality," but the dictionary doesn't know that. Lexio does, because it has the sentence in front of it. Across an article-length piece of reading, the difference between always-right and usually-right adds up to a different reading experience.
The extension is free for the kind of reading most people do — 20 lookups a month, no card, no account required to test. Lexio Pro removes the limit and unlocks two more reading modes (Balanced and Deep, using Gemini 2.5 Flash and Claude Sonnet 4.5 respectively) for $4.99/month. The pricing is the price of compute, not a markup; the extension's goal is to put a real reading tool in front of as many readers as possible.
Yes. The free plan gives you 20 word lookups per month, no credit card. Lexio Pro is $4.99/month and removes the limit, with a 3-day free trial. There is no separate price for the extension — it uses the same account as the website.
Yes — any PDF opened in Chrome (drag and drop, or visit a .pdf URL) works just like a regular web page. The only requirement is that the PDF has selectable text. For image-only scans, use Lexio's phone camera mode instead.
Any Chromium-based browser: Microsoft Edge, Brave, Opera, Arc, Vivaldi. The Chrome Web Store extension installs identically on all of them. Firefox and Safari extensions are on the roadmap; both require separate builds because their extension APIs differ.
Only the word you click and a short surrounding context window — roughly the sentence — are sent to the AI provider. The full page text is never sent. Lexio does not read pages in the background, does not log your browsing, and does not associate lookups with your identity beyond what is needed to enforce monthly limits.
You can look up words in English, Spanish, French, German, Italian, Portuguese, Dutch, Russian, Japanese, Chinese, and Arabic. Definitions can be returned in any of those languages — so you can read in English and get the answer in your native language.
Yes — Chrome blocks all extensions on a small number of system pages: the Chrome Web Store itself, chrome:// internal pages, and a few app-internal pages. Everywhere else on the web works.
The website is for when you have a passage to paste — useful for testing, for OCR scans, or for text that lives in a context Chrome can't open. The extension is for when you're already reading something online and don't want to context-switch. Most active users install both and use them for different parts of their reading day.
Free, takes 30 seconds, no account required to test. Works on every Chromium browser, every page you read, every PDF you open in the browser.