Adverb (fukushi), Adverb taking the 'to' particle, Suru verb
winding; meandering; zigzagging; zig-zag; in twists and turns; sinuously; tortuously
Onomatopoeic or mimetic word
さっきからやたらウネウネした道を進んでいる。I'm getting tired of driving on this winding road.
Also written ウネウネ