1. Not returned in kind
   "unrequited (unanswered) love"
   - unreciprocated, unrequited

See also: nonreciprocal

• undisclosed
• undiscouraged
• undiscoverable
• undiscovered
• undiscriminating
• undisguised
• undismayed
• undisputable
• undisputed
• undisputedly
• undissolved
• undistinguishable
• undistinguished
• undistorted
• undistributed
• undisturbed
• undiversified
• undividable
• undivided
• undivided interest
• undivided right
• undo
• undoable
• undock
• undocumented