function word; structure word; form word
Linguistics term for words that express grammatical relationships rather than carrying lexical meaning. Rare in everyday Japanese; the more common term is 機能語 (きのうご).
See also: 機能語
In linguistics, particles and auxiliary verbs are classified as function words.
内容語 (content word) is the opposite of 形式語, referring to words with independent lexical meaning.
Compound of 形式 (form) + 語 (word), calque from Western linguistic terminology.