knee jerk knee holm • knee joint · · · Info · Definitions · Synonyms · Characters · · knee jerk · · Text Common · · Latin · · Scripts 9 · · Length 2 · · Syllables Definitions · · · (noun) a reflex extension of the leg resulting from a sharp tap on the patellar tendon. Synonyms: knee jerk, knee-jerk reflex, patellar reflex. · · Noun Definition 1 Synonyms · · · knee-jerk reflex · · Synonym 1 patellar reflex · · Synonym 2 Characters · · space U+0020 e latin small letter e U+0065 j latin small letter j U+006A k latin small letter k U+006B n latin small letter n U+006E r latin small letter r U+0072