/ Thesaurus / U Synonyms of undefinable Find synonyms for: Adjective1. indefinable, undefinable, undefined (vs. defined), vagueusage: not capable of being precisely or readily described; not easily put into words; "an indefinable feeling of terror"; "an abstract concept that seems indefinable"WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: nefarious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language