To gasp with surprise or emotion; an archaic or poetic form of the verb 'gasp.'
From Old English 'gæsp' or related Germanic roots, with an archaic prefix 'a-' that indicates a state or condition (similar to 'ablaze'). The 'a-' intensified the meaning in Middle English.
You can see the prefix 'a-' in old words like 'agasp,' 'aflame,' 'ablaze'—it's a ghost of Old English grammar that made verbs describe someone being in a state ('gasping') rather than just doing an action.
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