An archaic or obsolete form meaning 'on the knee' or 'in a kneeling position,' used in Middle English texts.
From Old English a- (on) combined with knee, where the 'a-' prefix meant 'in a state of' or 'engaged in.' Over time this construction was replaced by modern phrasings like 'on one's knees.'
Middle English speakers could add 'a-' to almost any word to mean 'in that state'—so you could be afire, afoot, or atremble, making the language much more flexible than modern English.
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