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1. Not brought to a conclusion; subject to further thought
   "our position on this bill is still undecided";
   - open, undetermined, unresolved
    
2. Characterized by indecision
   "too many voters still declare they are undecided";
   - on the fence
    
3. Not yet having made a commitment
   "undecided voters"

1. A voter (etc.) who has not yet come to a decision

Derived forms: undecideds

See also: dithery, free-floating, indecisive, uncommitted, unsettled

Encyclopedia: Undecided