‘叭哒’ (bā dā) is a reduplicated onomatopoeic word that mimics short, wet, soft slapping or sucking sounds — like the noise made when lips part after suction, a frog’s tongue snapping back, or a duck’s beak closing on mud. The first character 叭 (bā) suggests a sharp, abrupt sound, while 哒 (dā) adds a softer, resonant follow-up, together forming a rhythmic, two-syllable auditory image. This word is not used for loud or harsh noises (like ‘bang’ or ‘crash’), but specifically for moist, gentle, often repetitive sounds associated with movement involving adhesion or release.

It appears most frequently in descriptive writing, children’s stories, and casual speech — especially when depicting animals (e.g., ducks, frogs, pigs) or human actions like licking, kissing, or stepping in puddles. While it carries no inherent emotion, context can make it playful, silly, or slightly gross. It functions grammatically as a noun (e.g., ‘发出叭哒声’) or an interjection (e.g., ‘叭哒！嘴一松就掉了’), and rarely stands alone without a verb or noun complement.