The Proto-Celtic word *gallo
Word *gallo
Meaning stone
Synonyms *arto, *krako

Other words that might be of interest
*kʷranno ‘tree’, *beljā ‘leaf, tree’, *tela-mon ‘earth’, *ūrā- ‘earth’, *φī-wer-jō(n) ‘land, earth’, *brig ‘mountain’, *monjo- ‘mountain’, *brendo- ‘hill’, *tumbo- ‘hill’