A traditional Fon name for the first son born after a set of twins. Independently attested both as a given name (borne by King Agaja before he took the throne) and as "Dossou", one of the single most common surnames in Benin today.
Source: Fon birth-order naming, cross-referenced across Wikipedia (Agaja) and Beninese surname-frequency data (surnam.es, "Dossou" — 59,745+ occurrences)