Gaping

google

ref

Middle English: from Old Norse gapa ; related to gap.

wiktionary

ref

From Middle English gaping, gapynge, variants of Middle English gapand, gapande, equivalent to gape +‎ -ing.

From Middle English gapynge, equivalent to gape +‎ -ing.

etymonline

ref

gaping (adj.)

"standing wide open," 1570s (implied in gapingly), present-participle adjective from gape (v.).