(w)

(pēng) impulsive

怦怦 (w)

(pēngpēng) thumping sound (onomatopoeia); to be eager and anxious (to do sth); faithful and upright

怦然 (w)

(pēngrán) with a sudden shock, bang etc

怦然心动 (w)

(pēngránxīndòng) palpitating with eagerness to do sth (idiom)