ことばの巣
Offline Japanese Dictionary
Free · In‑App Purchases · Designed for iPad. Not verified for macOS.
Kotobanosu is an offline Japanese dictionary where the words you look up stay with you.
No ads. No network access for looking words up. Looking up, reading and exporting are free.
■ Works with no signal
126,584 entries and 168,950 senses live inside the app.
Airplane mode, the subway, the mountains, a flight — it works the same everywhere.
■ Four ways in
・By word — spelling, reading, or romaji. The ordinary way
・By meaning — search the definition text. Type "ためらう" and reach "逡巡"
・By ending — search from the end of a word, for "〜ごころ" style searches
・By association — follow related words: synonyms, broader and narrower terms (paid)
You do not need to know the kanji. Hiragana, katakana and romaji all work.
Okurigana variations and variant characters are absorbed.
When nothing matches, read the text off a page with the camera (3 times a day for free).
■ Your lookups accumulate
Every word you look up is kept in "My Dictionary" automatically.
The free tier keeps the 10 most recent lookups within reach.
Favorites, tags, notes and the context where you met the word are paid features.
What is saved is the definition as it was when you read it.
Even if the dictionary data is rebuilt later, what you read stays as it was.
■ And then it comes back
People stop using dictionary apps because they look a word up and forget it.
Kotobanosu offers the word back before that happens.
・"You looked this up three months ago" — when you meet a word again. This one is free
・"Words you looked up around the same time" — the words that were beside it (paid)
・"Words with the same tag" — from the groupings you made yourself (paid)
・"Word of the day" — one a day. The notification is free, the widget is paid
You can also search your saved words by the memory of their meaning.
Even if the word itself is gone, "it meant something like hesitating" can find it.
■ AI on the device, and AI outside
・On the device — plain rephrasing, examples, usage, origin, English (3 times a day for free)
Shown only on devices with Apple Intelligence. Nothing leaves the device
・Ask an outside AI — a question is composed and opened in Safari for ChatGPT and
others (paid). You are always asked before anything is sent
■ Kanji too
13,108 kanji are included.
Readings, stroke count, school grade, JLPT level, and the words that use them.
■ Built for reading
Text size follows your iOS setting, and definitions stay readable when enlarged.
Definitions can be read aloud.
On iPad, a two-pane layout puts the list on the left and the definition on the right.
■ Your data is yours
Export your collected words as JSON, CSV, or Markdown.
JSON can be imported back. Exporting is never put behind the paywall.
■ Pricing
Looking up, reading and exporting are free.
The tools for keeping words — favorites, tags, notes, recall, association, widgets,
share cards, unlimited AI assists and camera lookups — are the paid tier.
・Monthly ¥200, yearly ¥1,600 (auto-renewing), or a one-time ¥4,000 (Japan)
・Monthly and yearly start with a 3-day free trial for new subscribers
・Auto-renewal can be turned off up to 24 hours before the period ends
・The one-time purchase does not renew
・Terms of Use (Apple standard EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
・Privacy Policy: https://muranakar.github.io/kotobanosu-site/privacy.html
■ What this app does not do
・No advertising
・No network access for looking words up (outside sites and AI open in Safari when you tap)
・Purchases and restores are handled by Apple. No payment details reach the developer
・No collection of user information. There is no mechanism to collect it
・Not a single analytics or tracking SDK
■ About the dictionary data
Built by combining Japanese Wiktionary, Japanese WordNet, SudachiDict, JMdict and KANJIDIC2.
No commercial publisher's dictionary is used.
Because it derives from openly edited data, there are errors and gaps.
Sources and licenses are listed in Settings > About.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
Minor improvements.
The developer, ryo muranaka, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Linked to You
The following data may be collected but it is not linked to your identity:
- Location
- Identifiers
- Usage Data
- Diagnostics
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- ryo muranaka
- Size
- 110.9 MB
- Category
- Reference
- Compatibility
Requires iOS 18.0 or later.
- iPhone
Requires iOS 18.0 or later. - iPad
Requires iPadOS 18.0 or later. - Mac
Requires macOS 15.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 2.0 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- In-App Purchases
Yes
- 買い切り $24.99
- 年額 $9.99
- 月額 $0.99
- Copyright
- © 2026 Ryo Muranaka