noun
front sandal strap; thong strap
Refers specifically to the strap of a sandal (like a zōri or geta) that passes between the big toe and second toe.
草履の前つぼが切れてしまった。
The front strap of my zōri broke.
前つぼの位置を調整すると歩きやすくなる。
Adjusting the position of the front strap makes it easier to walk.
鼻緒 is the general term for the thong strap of traditional Japanese sandals, while 前つぼ specifically refers to the front part of that strap.
Compound of 前 (mae, 'front') and つぼ (tsubo, 'jar' or 'pot'), likely referring to the shape or position of the strap. The exact derivation is uncertain.