head-shrinker

(slang, humorous) A psychiatrist.

Headshrink is a humorous, lightly irreverent term for a psychiatrist or therapist — a riff on the older slang 'shrink' (itself short for 'headshrinker'). It keeps the jokey vibe of the original while adding a little extra emphasis on the head. People use it when they want to talk about mental health professionals without sounding too clinical or too serious about the whole thing.

A back-formation from 'headshrinker', itself humorous slang for a psychiatrist or psychologist. The full form drew a darkly comic comparison between psychoanalysis -- probing and shrinking the psyche -- and headhunting practices of certain indigenous cultures. 'Headshrink' as a clipped form carries the same irreverent, mildly skeptical tone toward mental health professionals. The humor is gentle rather than hostile. Widely understood even by those who've never used it.

(US, colloquial) A psychiatrist.