geirr in Geir T. Zoëga(1910)A Concise Dictionary of Old Icelandic, Oxford: Clarendon Press
From Old Norse geirr(“spear”). Might also be a short form of Old Norse proper names with Geir- (such as Geirbrandr) or -geirr (such as Þorgeirr). In both cases from Proto-Germanic*gaizaz.
Cognate to Ger- as in German Gerhard and English Gerard and to Old English gār as in Edgar.