noun
struggle; writhing; floundering
Describes physical struggling, writhing, or floundering, often in a desperate or helpless manner. Can also be used figuratively for mental or emotional struggle.
溺れそうになって、必死のもがきを見せた。
About to drown, he showed desperate struggling.
彼の心の中のもがきが、表情に現れていた。
The struggle inside his heart showed on his face.
もがく is the verb form meaning 'to struggle, to writhe'; もがき is the noun form derived from it.
Noun form of the verb もがく (to struggle, to writhe). The verb itself is of uncertain origin, possibly related to mimetic or sound-symbolic roots.