To present participles which come from intransitive verbs, or are themselves employed as adjectives, to mark the absence of the activity, disposition, or condition implied by the participle;

not meant or adapted for a particular purpose; "a solvent unsuitable for use on wood surfaces"

not appropriate for a purpose or occasion; "unsuitable attire for the office"; "said all the wrong things"

not conducive to good moral development; "the movie is unsuitable for children"

not capable of being applied; "rules inapplicable to day students"

not worthy of being chosen (especially as a spouse)