1. [adj]  (music) characterized by musical dissonance; harmonically unresolved
2. [adj]  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"
3. [adj]  not solved; "many crimes remain unsolved"; "many problems remain unresolved"

UNRESOLVED is a 10 letter word that starts with U.