Knee-jerk

Alternative forms

• kneejerk
• knee jerk

Origin

en + knee + jerk, First attested 1876, obviously derived from a figurative sense of the patellar reflex.

Full definition of knee-jerk

Adjective

1. Unthinking, not carefully considered, (nearly) automatic, spontaneous, easily predictableHe gave a knee-jerk response.

Derived terms

• knee-jerkish
• knee-jerkishly
• knee-jerky

Noun

1. A sudden reflexive movement of the leg below the knee, as a reaction to a tap to the tendon just below the patella (kneecap).

Synonyms

• kneejerk reflex
• patellar reflex