Lookup — Instant Word Definitions

Select any word on a page or in a PDF to see its definition instantly.

A cross-browser extension that shows word definitions when you select (highlight) a word - on regular web pages and inside PDFs opened in a browser tab. What it does: 1) Select a word, get its meaning: highlight any word — or a short phrase — and the definition appears instantly next to it. Click the card to pin it, press Esc or select something else to dismiss it. 2) Fast lookups: the selected text is lowercased and sent to Wiktionary for a definition; if there is no dictionary entry the request falls back to a Wikipedia article summary. Misses are cached so repeated unknown words return instantly. 3) Falls back to a general search: if a word has no definition entry and no Wikipedia article, a general Wiktionary search offers related results instead. 4) Clean results: symbol-like entries (Symbol, Letter, Ligature, Character, Numeral, Translingual, …) are filtered out — only real meanings are listed. 5) PDFs use the browser's own viewer: PDFs open in the browser's built-in PDF viewer as normal. 6) Browsers don't expose text highlighted inside their viewers to extensions (and don't allow scripts to run there), so in PDFs the definition is triggered from the right-click menu: highlight a word, choose "Lookup", and the definition appears in the Lookup popup or a small Lookup window. 7) Privacy-friendly: no API keys, no accounts, no browsing-history collection. Words are only sent to the dictionary services when you select them, and results are cached locally.