hen [OE] Ultimately the word hen is related to Latin canere ‘to sing’. Hens do not have teeth, so to describe something as as rare as hen’s teeth is tantamount to saying that it is non-existent. The phrase hen’s teeth for something non-existent dates from 1700, but the full phrases with ‘as rare as’ or ‘as scarce as’ were originally used in the USA from the mid 19th century. Henpecked goes back to the mid 17th century. The expression comes from the way that hens will sometimes peck at the feathers of other birds.