An archaic or poetic word for a heron, a tall wading bird with long legs and a sharp beak.
From Old English hearn or heron, from Proto-Germanic; the word 'hern' survived in dialect and poetry while 'heron' became the standard modern term.
Medieval poets loved calling herons 'herns'—it sounds more magical and mysterious than the modern word, which is probably why it shows up in old legends!
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