Lacking grace in movement or posture "a gawky lad with long ungainly legs"; "what an ungainly creature a giraffe is" - gawky, clumsy, clunky, unwieldy, klutzy [N. Amer]
Difficult to handle or manage especially because of shape "the cello, a rather ungainly instrument for a girl" - awkward, bunglesome, clumsy
Derived forms: ungainlier, ungainliest
See also: awkward, ungainliness, unmanageable, unwieldy