appropriate response; expedient action
Refers to acting flexibly and appropriately according to changing circumstances. Most commonly encountered in the set phrase 臨機応変 (りんきおうへん), meaning 'adapting to the situation' or 'playing it by ear'. As a standalone noun, usage is somewhat limited and often formal or written.
This job requires the ability to respond flexibly to changing circumstances.
We need to take appropriate measures according to the situation.
adapting to the situation; playing it by ear; ad hoc
adaptability; ability to respond flexibly
Compound of 応 (おう, 'respond') and 変 (へん, 'change'), literally meaning 'responding to change'. The exact historical derivation is uncertain, but it is a Sino-Japanese word (kango) that became established through classical Chinese influence.