Stare open-mouthed is an expression used to describe a person who is looking at something with their mouth wide open in shock or amazement. GAPE, GAWP, and GAWK are all synonyms for this expression, with GAPE being the most commonly used. GAPE is defined as to look with the mouth wide open, usually in wonder or astonishment. GAWP is defined as to stare with the mouth open, usually in surprise or admiration. GAWK is defined as to stare stupidly or foolishly, especially with the mouth open. All three words can be used to describe someone who is staring open-mouthed.