English poet John Milton put a variant of aerie to good use in Paradise Lost (1667), writing, "… there the eagle and the stork / On cliffs and cedar tops their eyries build." But Milton wasn't the first to use the term, which comes to us via Medieval Latin and Old French and probably traces to an earlier Latin word, ager, meaning "field." English speakers had been employing aerie as a word for a bird's nest for more than a century when he penned those words. Eventually, aerie was applied to human dwellings as well as birds' nests. At first, this sense referred to dwellings nestled high up in mountains or hills. These days, you're also likely to hear high-rise city apartments or offices referred to as "aeries."