quasi-synonymy; near-synonymy
Technical term in linguistics and computing for words that are similar but not fully interchangeable in meaning.
Words with high quasi-synonymy must be used differently depending on the context.
This study proposes a method to quantify quasi-synonymy between words.
類義語 is a near-synonym (a word), while 類義性 is the abstract property of being near-synonymous.
Compound of 類義 (るいぎ, 'similar meaning') + 性 (せい, '-ness, property'). The exact historical derivation is uncertain; the term is used in modern technical contexts.