Short answer: use ChatGPT when you want to talk about a word: ask follow-up questions, get more examples, compare two similar words, or translate into your own language. Use QuickDef when you are in the middle of reading and want a quick, plain-English explanation of a word or phrase without leaving the page. Many English learners use both: QuickDef for the 20 lookups in an article, ChatGPT for the one word they want to understand deeply.

Pasting a confusing sentence into ChatGPT has become one of the most common ways people check what a word means. It works well, because ChatGPT reads the whole sentence and explains the meaning that fits. QuickDef does the same kind of explanation, but inside the page you are reading. In fact, QuickDef's AI definitions are written by an OpenAI model too (GPT-4o-mini). The difference is in how you get the answer and what happens afterwards.

Side-by-Side Comparison

	ChatGPT	QuickDef
How you look up a word	Copy the word or sentence, switch to ChatGPT, write a question	Double-click the word on the page
Uses the sentence to pick the meaning	Yes, if you paste the sentence	Yes, automatically
Explains phrases and idioms	Yes	Yes (drag across 2–7 words)
Plain-English level for learners	Yes, if you ask for it	Yes, by default (A2–B1 CEFR)
Follow-up questions and more examples	Yes	No
Translates into your language	Yes	No (English explanations only)
Works on PDFs	Yes, by uploading the file or pasting text	Yes, in QuickDef's own PDF reader
Saves words for review	No word list (past chats are kept)	Saved words with their sentence, plus flashcards
Traditional dictionary entry with pronunciation	Not by default	Yes (dictionary mode, with audio where available)
Price	Free plan with unlimited text chats; paid plans for more features	Free (10 AI definitions/day, unlimited dictionary lookups, 25 saved words) / Premium $3.99/mo or $29.99/yr

Checked October 2026.

Where ChatGPT Is Better

You can keep asking. After the first explanation you can ask "Can you give me three more examples?", "Is this formal?", or "What's the difference between affect and effect?" A conversation is the best way to really learn a difficult word, and no dictionary extension can match it.

It translates. Ask for the meaning in Indonesian, Turkish, Spanish, or almost any other language, and ChatGPT will answer in that language. QuickDef explains in simple English only.

It handles whole paragraphs. If a full paragraph is confusing, not just one word, ChatGPT can rewrite it in simpler English or summarize it.

The free plan is generous. Since August 2026, ChatGPT's free plan allows unlimited text chats (PCWorld), so cost isn't a reason to avoid it. Uploads and some other features still have limits.

Limits to know:

Every lookup means leaving the page: select, copy, switch tab, paste, type a question, read, switch back. For one word that's fine. For the 15 or 20 words in a hard article, it breaks your reading.
If you paste only the word, ChatGPT has to guess which meaning you need. You get a better answer when you paste the whole sentence, which is more copying.
Words you looked up stay buried in chat history. There is no list to review later unless you build one yourself.

Where QuickDef Is Better

It is much faster while reading. Double-click a word and the explanation appears right next to it. You don't copy anything, switch tabs, or write a prompt, so you keep your place in the text.

It sends the sentence for you. QuickDef reads the sentence around the word, so "bank" in a finance article and "bank" in a geography text get different answers. You get the right meaning without having to paste context.

It explains phrases in place. Drag across 2–7 words and click Define. This covers phrasal verbs, idioms, and fixed expressions like "bear out" or "a piece of cake". Why normal dictionaries struggle with these.

Its answers are short on purpose. Explanations use simple vocabulary (around CEFR A2–B1) and stay brief, so you understand the word and go back to reading. ChatGPT often gives a longer answer than you need mid-sentence.

It builds your vocabulary list. Save a word and QuickDef keeps the sentence you found it in. Review saved words as flashcards later, which is much easier than searching old chats.

It works on PDFs. Click Open PDF in the QuickDef toolbar popup and paste the PDF's link or choose a file. It opens in QuickDef's own PDF reader, where double-click lookups work like on a webpage. More on looking up words in PDFs.

Limits to know:

No conversation. You get one explanation per lookup and can't ask a follow-up question.
The free plan includes 10 AI definitions per day and 25 saved words. Dictionary-mode lookups are unlimited. Premium removes both limits.
English explanations only, and no translation into your native language.
Chrome and Chromium browsers only, no mobile.

Same Sentence, Two Workflows

Say you are reading this in a news article:

"The minister said the new data would bear out the government's decision."

With ChatGPT: select the sentence, copy it, open the ChatGPT tab, paste it, type "What does bear out mean here?", and wait. You get a clear answer, often with a few extra examples. Then you switch back and find your place again. That's usually 20 seconds or more.

With QuickDef: drag across "bear out" and click Define. A short explanation appears next to the phrase, roughly: to show that something is true; here, the data will prove the decision was right. You never leave the article.

If this is the only word you don't know, either way is fine. If you are reading a long article in your second language, those extra 20 seconds add up quickly.

Which One Should You Use?

Choose ChatGPT if you:

Want to discuss a word, ask follow-ups, or see many examples
Want explanations or translations in your native language
Need a whole paragraph simplified, not just one word

Choose QuickDef if you:

Read long articles, papers, or ebooks in English as a second language
Look up many words per session and don't want to keep switching tabs
Get stuck on phrasal verbs and idioms
Want a saved word list with real example sentences to review

Use both if you: want speed while reading and depth afterwards. Use QuickDef to get through the text, save the words that matter, then take the hardest ones to ChatGPT for more examples and practice.

Add QuickDef to Chrome, free

Frequently Asked Questions

Is ChatGPT good for looking up word meanings?

Yes. ChatGPT gives accurate, context-aware explanations, especially when you paste the whole sentence and not just the word. Its weakness for reading is speed: each lookup means copying text and switching tabs, which interrupts long reading sessions.

Is QuickDef the same as ChatGPT?

No. QuickDef uses an OpenAI model (GPT-4o-mini) to write its definitions, but it is a Chrome extension built for one job: explaining a word or phrase in simple English, right on the page, using the sentence around it. It doesn't support conversations or follow-up questions.

Is ChatGPT free for looking up words?

Yes. As of August 2026, ChatGPT's free plan allows unlimited text chats, though uploads, image generation, and some other features still have limits.

Is QuickDef free?

Yes, QuickDef has a free plan with 10 AI definitions per day, unlimited dictionary lookups, and 25 saved words. Premium costs $3.99/month or $29.99/year and removes the limits.

Can ChatGPT explain words in a PDF?

Yes, if you upload the PDF or paste its text into a chat, though file uploads are limited on the free plan. QuickDef opens PDFs in its own reader, where you double-click a word to see its meaning without uploading anything to a chat.

Features and pricing checked October 2026. Both products change often; check OpenAI's and QuickDef's sites for the latest details.

QuickDef vs ChatGPT for Looking Up Words: Which Is Better? (2026)