Word Watch is a Keyword Research Tool with a built-in thesaurus dictionary

It allow you to search thesaurus dictionary offline on your iPhone or AppleWatch

【 Features 】
This Thesaurus dictionary has been created uniquely using OpenSource services called WordNet and MobyThesaurus, adding up to 150,000 words.
The latest proper nouns may not be included, but highly versatile nouns, verbs, adjectives, and adverbs are included evenly.
Unlike the regular Thesaurus dictionary, the definitions are excluded. Only synonyms and related words are included, and are linked to each other.
Using the link of 150,000 words, You can browse the dictionary by just tapping the word link