Synonyms that are in the dictionary are marked in green. Synonyms that are not in the dictionary are marked in red.
Antonyms that are in the dictionary are marked in green. Antonyms that are not in the dictionary are marked in red.
Those learners can try Pleco (for Chinese) and Kanji Recognizer (for Japanese, Android only), which are essentially dictionary apps and provide more detailed translations and shades of meaning.