Fir Bolg 
(fîr b
ŏlg, b
ŏl
əg)
pl.n. Mythology 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 the Appendix of 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 the Appendix of Indo-European roots.]