'bang' originates from imitative/onomatopoeic origin in English, reflecting the sound of a sudden loud noise.

'bang' appeared in Middle English and was used to imitate a sharp, sudden sound; the verb sense "to strike" developed from that imitative use and the modern noun and verb forms evolved from those early usages.

Initially, it was primarily an imitative word for a sudden loud noise; over time it also came to mean the action of striking and to be used for related figurative senses (e.g., dramatic endings, sexual slang in informal contexts).