knee-jerk /ˈniːˌʤɚk/ adjective Learner's definition of KNEE-JERK
always used before a noun [more knee-jerk; most knee-jerk]
1
: occurring quickly and without thought未经思索产生的；下意识的；无意识的 2
disapproving : often reacting quickly and without thought不假思索立即做出反应的；冲动的