no obj.
1- adopt a position where the knees are bent and the upper body is brought forward and down, typically in order to avoid detection or to defend oneself（常指为防止被发现或自卫而）蹲; 蹲伏：
we crouched down in the trench
我们在战壕里蹲下
(be crouched) Leo was crouched before the fire.
利奥蹲在炉火前。
1.1
crouch over
bend over so as to be close to (someone or something)向（某人或某物）俯身过去：she was crouching over some flower bed.
她对着一个花坛俯身过去。
词源
late Middle English: perhaps from Old French crochir 'be bent', from croche （see CROTCH）.