A people who invaded and inhabited Ireland. They were defeated by the Tuatha Dé Danaan.
[Irish, from Old Irish : fir, plur. of fer, man; see wī-ro- in Indo-European roots + bolg, perhaps genitive plur. of bolg, bag (literally, "men of bags," perhaps from the notion that warriors "swell" with heroic valor in battle ); see bhelgh- in Indo-European roots.]