From Old Galician-Portuguese avoo, from Vulgar Latin *av(i)olum, ultimately from Latin avus, from Proto-Indo-European *h₂éwh₂os (“grandfather”).
avô m (plural avôs, feminine avó, feminine plural avós)
- grandfather, male grandparent
Avô has two plural forms, avôs and avós. The former (os avôs) means exclusively a group of two or more men (cf. English grandfathers), the latter (os avós) is used for a group of both men and women (cf. English grandparents). Both are masculine nouns. The plural of avó (grandmother) is a regular feminine noun (as avós) and means grandmothers. This is one of the few Portuguese nouns that have a tripartite plural inflection, the others being sogro, consogro, tio-avô, bisavô and other derived terms.