as cowardly as a mouse;as timid as a hare; cannot (/be unable to) say boo to a goose; chicken-hearted; faint-hearted ❍ 嘿！ 此人～，却也可笑！ (朱素臣《十五贯》32) Pah! What a coward! Ridiculous!
胆小如鼠
as timid as a mouse;chicken-hearted 表面上气壮如牛，内心中～ outwardly as strong as a bull,but inwardly as timid as a mouse
胆小如鼠dǎn xiǎo rú shǔ
胆子小得如老鼠。as timid as a mouse, as cowardly as a mouth, mouselike timidity, chicken-hearted, faint-hearted, cannot say bold to a goose, have not the courage of a chicken