Entry
  1. Adverb (fukushi), Adverb taking the 'to' particle, Na-adjective (keiyodoshi), Suru verb

    trembling (with fear, cold, etc.); shaking; chattering (of teeth)

    Onomatopoeic or mimetic word

    少し走っただけで膝がガクガクしてるよ。
    All I did was run a little and now my knees are wobbly.
  2. coming loose; wobbling

    Onomatopoeic or mimetic word

Also written がくがく

Pitch on OJAD