Word parts in- + definite Pronunciation IPA (key): /ɪnˈdɛfɪnɪt/ Audio (UK)(file) Hyphenation: in‧def‧i‧nite Adjective Positive indefinite Comparative none Superlative none If a time is indefinite, it is not known how long it is. Synonym: unclear She'll be staying with us for an indefinite period of time. Perhaps even a few months. Related words indefinitelyWikiwand - on Seamless Wikipedia browsing. On steroids.