onomatopoeic word meaning limp, floppy, or soft and easily deformed; used for objects or body parts that are limp or wobbly.
運動不足で筋力が落ち、腕がぐにゃぐにゃになった気がする。
From lack of exercise my muscles are weak and my arms feel floppy.
このゴムは古くてぐにゃぐにゃだ。もう使えない。
This rubber is old and floppy. It can't be used anymore.
急いで描いた字がぐにゃぐにゃで読みにくい。
The handwriting I rushed is all wobbly and hard to read.