also ogam, ancient Irish form of writing, 1620s, from Irish ogham, from Old Irish ogam, said to be from name of its inventor, Ogma Mac Eladan. But this appears to be from Celt. *Ogmios, perhaps from PIE *og-mo- "furrow, track," thus metaphorically "incised line." This could be the source of the name of the writing style, which looks like a series of cuts or incised lines, and the inventor's name thus might be folk etymology. Related: Oghamic.