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Dictionaries you buy once.

Buy Dictionary and Thesaurus Pro. It is the best-reviewed of these by a clear margin, it works with no signal, and it carries a thesaurus too. Merriam-Webster is the one to buy if the name on the definition matters to you. LDOCE is for people learning English rather than people who already speak it, and Roget's II is a specialist thesaurus with an interface to match its age.

The filter. Every app here is a single purchase. None of them can start charging you monthly for what you already bought. See every app under this rule ›
Top pick

Dictionary and Thesaurus Pro

Farlex, Inc.
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$9.99 once4.9★ (2,563)Updated Apr 2, 2026
Verdict
Reviewers consistently praise its offline dictionary and thesaurus content and call it easy to use, with several explicitly contrasting the one-time fee against subscription-based rivals like Merriam-Webster.
Best for
Someone who wants a comprehensive dictionary and thesaurus they can look words up in without a data connection, and who's tired of subscription dictionary apps.
The catch
At least one reviewer notes the audible pronunciation feature doesn't work offline, so some functionality still needs a connection.
One-time purchaseWorks offlineNo adsThesaurus

Merriam-Webster Dictionary+

Merriam-Webster, Inc.
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$9.99 once4.8★ (22,260)Updated Sep 22, 2026
Verdict
A well-regarded dictionary app that reviewers say works offline after the one-time purchase, without ads or subscription upsells, though a handful of users report crashes.
Best for
Someone who wants a reliable, ad-free dictionary they can look words up in without a data connection, and who paid once instead of dealing with in-app subscription prompts.
The catch
A small number of reviewers report the app crashing on open or when saving words, so stability isn't universal.
One-time purchaseWorks offlineApple Watch

English Dictionary - LDOCE PRO

Nguyen Thi Hoai Thu
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$14.99 once4.7★ (2,208)Updated Oct 3, 2025
Verdict
Reviewers repeatedly complain that offline access is broken or missing after updates, which undercuts the main reason someone would buy a dictionary app instead of using a website. Performance also slowed down for some users after a recent update.
Best for
Someone who mostly has a data connection and wants a comprehensive Longman-based dictionary on their phone, not someone relying on it in airplane mode or with no signal.
The catch
Multiple recent reviews say offline mode stopped working after an update, or never worked at all, which is a serious problem for a dictionary app people buy specifically to use offline.
One-time purchaseLearner's definitionsPronunciation

Roget's II: New Thesaurus

Enfour, Inc.
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$4.99 once4.7★ (373)Updated Oct 12, 2026
Verdict
Reviews describe crashes on recent OS versions and a cramped, single-window layout that dumps all results into tiny print without font controls. That's a rough experience for an app whose whole job is readability.
Best for
Someone who already owns Roget's II in print and just wants occasional offline word lookups on an older iPad, and won't mind a dated interface.
The catch
Multiple reviewers report crashes on updated OS versions and a cluttered single-window display that's hard to read.
One-time purchaseThesaurus onlyVery large

Side by side.

AppPriceWorks offlineThesaurusSourceUpdated
Dictionary and Thesaurus Pro$9.99 once YesYesTheFreeDictionaryApr 2, 2026
Merriam-Webster Dictionary+$9.99 once YesYesMerriam-WebsterSep 22, 2026
English Dictionary - LDOCE PRO$14.99 once DisputedNoLongmanOct 3, 2025
Roget's II: New Thesaurus$4.99 once YesOnlyRoget's, MobyOct 12, 2026

Who should skip this entirely.

iOS has a dictionary built in — select any word, tap Look Up, and it is there, offline, for nothing. For most people that is the end of the question. These are worth paying for when you want a specific publisher's definitions, a proper thesaurus, or a learner's dictionary written in simpler English than the built-in one uses.

Questions.

Is the built-in iOS dictionary any good?Yes, and it is free. It draws on the New Oxford American Dictionary and works offline. Buy one of these when you want a different publisher, a real thesaurus, or learner-level definitions.
Which of these works with no signal?All of them claim to. Reviewers only dispute it for LDOCE, where several say the offline content they paid for was missing.

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