gape

from The American Heritage® Dictionary of the English Language, 5th Edition.

• intransitive verb To open the mouth wide.
• intransitive verb To stare wonderingly or stupidly, often with the mouth open. synonym: gaze.
• intransitive verb To be or become open or wide.
• noun The act or an instance of gaping.
• noun A large opening.
• noun The mouth, especially when open.
• noun Zoology The width of the space between the open jaws or mandibles of a vertebrate.
• noun A disease of birds, especially young domesticated chickens and turkeys, caused by gapeworms and resulting in obstructed breathing.
• noun A fit of yawning.

from The Century Dictionary.

• noun The act of gaping.
• noun A fit of yawning: commonly in the plural.
• noun In zoology:
• noun The width of the mouth when opened; the interval between the upper and under mandibles; the rictus, or commissural line. See first cut under bill.
• noun The gap or interval between the valves of a bivalve mollusk where the edges of the valves do not fit together when the shell is shut. See gaper, 4.
• noun plural A disease of young poultry, caused by the presence of a nematoid worm or strongyle (Syngamus trachealis) in the windpipe, attended by frequent gaping as a symptom.
• To open the mouth involuntarily or as the result of weariness, sleepiness, or absorbed attention; yawn.
• According to the inducing cause of the gaping, the verb, without losing its literal meaning, usually takes on an additional specific sense.
• To yawn from sleepiness, weariness, or dullness.
• To open the mouth for food, as young birds.
• Hence — To open the mouth in eager expectation; expect, await, or hope for, with the intent to receive or devour. See phrases below.
• To stand with open mouth in wonder, astonishment, or admiration; stand and gaze; stare. See phrases below, and gaping.
• To open as a gap, fissure, or chasm; split open; become fissured; show a fissure.
• To stand in eager expectation of; covet; desire; long for.
• To covet, desire; long for.
• Synonyms Gaze, etc. See stare.

from the GNU version of the Collaborative International Dictionary of English.

• intransitive verb To open the mouth wide.
• intransitive verb Expressing a desire for food.
• intransitive verb Indicating sleepiness or indifference; to yawn.
• intransitive verb Showing unselfconsciousness in surprise, astonishment, expectation, etc.
• intransitive verb Manifesting a desire to injure, devour, or overcome.
• intransitive verb To open or part widely; to exhibit a gap, fissure, or hiatus.
• intransitive verb To long, wait eagerly, or cry aloud for something; -- with for, after, or at.
• noun The act of gaping; a yawn.
• noun (Zoöl.) The width of the mouth when opened, as of birds, fishes, etc.
• noun A disease of young poultry and other birds, attended with much gaping. It is caused by a parasitic nematode worm (Syngamus trachealis), in the windpipe, which obstructs the breathing. See Gapeworm.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• verb intransitive To open the mouth wide, especially involuntarily, as in a yawn, anger, or surprise.
• verb intransitive To stare in wonder.
• verb intransitive To open wide; to display a gap.
• noun uncommon An act of gaping; a yawn.
• noun A large opening.
• noun A disease in poultry caused by gapeworm in the windpipe, a symptom of which is frequent gaping.
• noun zoology The width of the mouth (of a bird, fish, etc.) when it is open.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• verb look with amazement; look stupidly
• verb be wide open
• noun a stare of amazement (usually with the mouth open)
• noun an expression of openmouthed astonishment