心虚

心虚	xīn xū	lacking in confidence / diffident / to have a guilty conscience
心	xīn	heart / mind / intention / center / core / CL:颗,个
虚	xū	emptiness / void / abstract theory or guiding principles / empty or unoccupied / diffident or timid / false / humble or modest / (of health) weak / virtual / in vain