not brought to a conclusion; subject to further thought; "an open question"; "our position on this bill is still undecided"; "our lawsuit is still undetermined"

characterized by indecision; "some who had been on the fence came out in favor of the plan"; "too many voters still declare they are undecided"

not yet having made a commitment; "undecided voters"

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;

"Undecided" is a popular song.