Meaning

noun an expression of openmouthed astonishment

noun a stare of amazement (usually with the mouth open)

verb look with amazement; look stupidly

originFrom Middle English gapen, from Old Norse gapa (“to gape”) (compare Swedish gapa, Danish gabe), from Proto-Germanic *gapōną (descendants Middle English geapen, Dutch gapen, German gaffen), perhaps from Proto-Indo-European *ǵʰеh₂b-. Cognates include Russian зяпа (zjapa). Doublet of gap.

Etymology from Wiktionary, CC BY-SA 3.0