1. Not even or uniform as e.g. in shape or texture
   "uneven margins"; "wood with an uneven grain"; "an uneven colour"; "uneven ground"
    
2. (of a contest or contestants) not fairly matched as opponents
   "vaudeville … waged an uneven battle against the church";
   - mismatched
    
3. Variable and recurring at irregular intervals
   "an uneven gait"; "uneven spacing"
    
4. Lacking consistency
   "the golfer hit the ball well but his putting was uneven";
   - spotty, scratchy

See also: crinkled, crinkly, cross-grained, curly-grained, evenness, inconsistent, invariability, irregular, jagged, jaggy, lumpy, one-sided, out of true, patchy, pebble-grained, ragged, raggedy [N. Amer], raggy [informal], rippled, rough, scraggy, unequal, unparallel, unsmooth, unsteady, untrue, wavelike, wavy, wavy-grained

Antonym: even