丫叉的英語是?

slingshot 是對的, 是"彈弓", 是美式用法. 還有 "catapult" 是同義詞, 是英式用法.
slingshot= catapult:
a stick shaped like a Y with a rubber band attached to it, used by children for shooting stones.

2007-09-28 13:27:16 補充：
crotch 是分叉, 可以用於一切物件, 如褲衩, 路叉, 但不是用來玩的彈弓