應

Phono-semantic compound:

心 (마음 심) — semantic, denoting the mind, emotion, or internal response.

䧹 (응 / 매 응) — phonetic, the original form depicting a bird atop a structure (symbolizing quick, perceptive response).

In bronze inscriptions (金文 jinwen), 䧹 appears as a bird (隹) with an added radical indicating enclosure or posture — suggesting attentiveness or readiness.

The combination with 心 conveys “a movement or stirring in the heart in response to something external,” hence “to respond, to answer.”

감응 (感應) — mutual response; sympathetic resonance

대응 (對應) — correspondence, counteraction

반응 (反應) — reaction, response

응급 (應急) — emergency response

응답 (應答) — reply, answer

응용 (應用) — application, practical use

응원 (應援) — cheering, support

적응 (適應) — adaptation

호응 (呼應) — to respond to a call, to echo

응당 (應當) — ought to, should

Common idioms:

應有盡有 — “everything one could wish for.”

應聲而起 — “to rise at once in response to a call.”

應運而生 — “to arise in response to the times.”

In Confucian and Daoist texts, 應 signifies the harmonious correspondence between Heaven, Earth, and humankind.

For instance:

《中庸》: “天命之謂性，率性之謂道，修道之謂教。道也者，不可須臾離也；可離，非道也。”

Human virtue 應天而行 — “acts in response to Heaven’s mandate.”

《莊子》: “以無心應物，而不以物傷性。”

“Respond to things with an unperturbed heart, unmoved by external change.”

In military and strategic contexts (e.g., 策應), it means “to coordinate or respond to an ally’s movement.”

The simplified form 应 originated from the cursive version of 應 — reducing 隹 to a few strokes and 心 to a single line.