1.Definition: (used especially of persons) not dependable in devotion or affection; unfaithful
"When lovers prove untrue"
2.Definition: not according with the facts
"Unfortunately the statement was simply untrue"
3.Definition: not accurately fitted; not level
"Off-level floors and untrue doors and windows"
4.Definition: not true to an obligation or trust
"Is untrue to his highest opportunity and duty"