With a smack or loud sound; in a manner producing a sharp hitting sound.
From 'a-' plus 'smack,' where 'smack' comes from Middle Dutch 'smac' or Low German 'smack,' imitating the sound of a blow or impact. This onomatopoetic root makes the word sound like what it describes.
It's brilliant that onomatopoeia like 'smack' could take the 'a-' prefix to become 'asmack'—imagine the phrase 'he fell asmack against the door' with the word actually sounding like the impact it describes.
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