From Old French *grandir*, derived from *grand* ("big, great"), which itself comes from Latin *grandis* ("full-grown, large"). The suffix *-ir* marks it as a second-group French verb, following the pattern of verbs like *finir* and *choisir*.

In French, *grandir* covers both physical growth ("il a grandi de cinq centimètres" — he grew five centimetres) and emotional or social maturity ("cette expérience m'a fait grandir" — that experience made me grow as a person). The figurative use is very common in everyday speech and literature alike. False-friend alert for Spanish speakers: Spanish *grande* means "big/old," but *grandir* in French is always about the *process* of growing, not the state of being big (for that, French uses *grand/grande*).