also ogam, name of an ancient Irish and Celtic form of writing using a 20-character alphabet, 1620s, from Irish ogham, from Old Irish ogam, said to be from name of its inventor, Ogma Mac Eladan. Tthis appears to be from Celtic *Ogmios, perhaps from PIE *hog-mo- "trajectory; furrow, track," thus metaphorically "incised line." The writing style looks like a series of cuts or incised lines. The inventor's name thus might be folk etymology. Lucian, writing in Greek, records Ogmios as the name of a Gaulish deity. The PIE word is perhaps also the source of Sanskrit ajma "course, road." Greek ogmos "a straight line," Related: Oghamic.