out of one's depth

out of (one's) depth

In a field or situation that exceeds one's knowledge or ability. Of course she's out of her depth with 25 employees reporting to her—she had hardly any supervisory experience before you gave her the job! I asked Alex to consult on this project because it's a bit out of my depth.
See also: depth, of, out

out of one's depth

Also, beyond one's depth. Outside one's understanding or competence, as in He was out of his depth in that advanced calculus class, or The conductor realized that playing the fugue at the right tempo was beyond their depth . This expression alludes to being in water so deep that one might sink. [c. 1600] Also see over one's head.
See also: depth, of, out