Standard Lemma guide

knee-jerk

adj · noun · 2 senses · updated from the 2026-07-25 local source snapshot

Definitions and examples are grouped by meaning. Pronunciation, history, word forms, translations, descendants, synonyms, antonyms, derived terms, and related words appear whenever the source provides them.

Sound

Pronunciation

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1

adj

Meaning 1

Unthinking, not carefully considered, (nearly) automatic, spontaneous, easily predictable.

Definition source: English Wiktionary via Wiktextract

Examples

  • He gave a knee-jerk response.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

2

noun

Meaning 2

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

Definition source: English Wiktionary via Wiktextract

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

History

Etymology

From knee + jerk, First attested c. 1876, and derived from a figurative sense of the patellar reflex.

Across languages

Translations

22 source translations are retained for this English entry.

  • Dutch: voorspelbaar — reacting unthinkingly or spontaneously in an expected manner
  • Finnish: refleksinomainen vastaus — reacting unthinkingly or spontaneously in an expected manner
  • Finnish: selkäydin- (such as selkäydinreaktio) — reacting unthinkingly or spontaneously in an expected manner
  • French: prévisible — reacting unthinkingly or spontaneously in an expected manner
  • German: reflexartig — reacting unthinkingly or spontaneously in an expected manner
  • German: vorhersehbar — reacting unthinkingly or spontaneously in an expected manner
  • German: automatisch — reacting unthinkingly or spontaneously in an expected manner
  • Icelandic: ósjálfráður — reacting unthinkingly or spontaneously in an expected manner
  • Spanish: impulsivo — reacting unthinkingly or spontaneously in an expected manner
  • Spanish: visceral — reacting unthinkingly or spontaneously in an expected manner
  • Finnish: patellaarirefleksi — reflex extension of the lower leg due to tap below knee
  • Finnish: polviheijaste — reflex extension of the lower leg due to tap below knee
  • German: Kniereflex — reflex extension of the lower leg due to tap below knee
  • German: Kniesehnenreflex — reflex extension of the lower leg due to tap below knee
  • German: Patellarreflex — reflex extension of the lower leg due to tap below knee
  • German: Patellarsehnenreflex — reflex extension of the lower leg due to tap below knee
  • German: Kniephänomen — reflex extension of the lower leg due to tap below knee
  • Icelandic: hnéviðbragð — reflex extension of the lower leg due to tap below knee
  • Icelandic: hnékippur — reflex extension of the lower leg due to tap below knee
  • Norwegian: knerefleks — reflex extension of the lower leg due to tap below knee
  • Norwegian: patellarefleks — reflex extension of the lower leg due to tap below knee
  • Spanish: reflejo rotuliano — reflex extension of the lower leg due to tap below knee