noun, noun which may take the genitive case particle 'no'
Used to state that two words or expressions have the same meaning. Often appears in the pattern 同義である or as a noun modifier with の.
この二つの語は同義である。
These two words have the same meaning.
These two words are almost synonymous.
同義の表現を探す。
Look for a synonymous expression.
Some people use 'big' and 'huge' as synonyms.
同義 specifically means 'same meaning' or synonymous, matching 同意's third sense, but 同義 carries no consent meaning.
異義 means a different meaning, the direct opposite of 同義 which means the same meaning, as contrasted in terms like 同音異義語.
同意 usually means agreement or consent, while 同義 means that two words or expressions share the same meaning; the similar sound and shared 同 kanji can cause confusion.
From 同 (same) + 義 (meaning). The kanji compound directly conveys the idea of identical meaning.