The Noble and the Most Ancient House of Black - Licorus Black's generation
Licorus Nigellus Black (1808 - 1872): eldest son and heir, naturally, the middle name is after his father. Licorus is a form of the name Lycorus. In Greek mythology, Lycorus was a son of the god Apollo. Nigellus is of Latin origin, meaning "champion", or "dark-haired".
Phoebe Prosperine Black (1810 - 1882): middle name after Prosperine ofc, Phoebe is an odd name for a family with constellation theme but Phoebe is also the name of a moon of Saturn that is described as being lamp black in colour. This loosely fits in with the Black family tradition of using celestial names for their children.
Alexia Concordia Walkin Black (1812 - 1900): Her mother's heiress. Her middle name is after her mother, and also she took Walkin as a name.. which is pretty obvious.
Eduardus Leto Limette Black (1820 - 1899): Eduardus is a Latin form of the name Edward, meaning "prosperous, blessed guard". Leto is of Greek origin, meaning "hidden", or "forgotten" which seems to fit well since Eduardus was disowned, hence "forgotten" by later members of the family.
Hesper Plaides Black (1820 - 1820): The name Hesper comes from the Greek Hesperos (Ἕσπερος), meaning "evening star" — typically referring to the planet Venus when it appears in the evening sky.