Pluto and its Moons

The dwarf planet Pluto has five known moons. In order of distance from Pluto they are Charon, Styx, Nix, Kerberos, and Hydra.
The following are origins and meanings of them all.

 

Pluto: Via Latin from Greek Plouton (Pluto, the god of the underworld). The adjective is plutonian: 1. Relating to the dwarf planet Pluto. 2. Relating to Pluto, the god of the underworld in the Greek mythology. 3. Relating to the underworld.  Hades was the ancient Greek god of the underworld. Eventually, the god's name came to designate the abode of the dead. In Greek mythology, Hades is the oldest male child of Cronus and Rhea. Later, the Greeks started referring to the god as Plouton, which the Romans Latinized as Pluto.

 

Charon: The ferryman of the dead, closely associated in myth with the god Hades. The word is a noun meaning any boatman.

 

Styx: In Greek mythology Styx was a river in the underworld over which souls of the dead were ferried by Charon. Styx was also the river by which oaths were sworn that even gods were afraid to break. The word is from Latin Stygius, from Greek Stygios, from Styx (the hateful). The word is Stygian, an adjective meaning 1. Dark or gloomy. 2. Hellish. 3. Unbreakable or completely binding (said of an oath). 4. Relating to the river Styx.

 

Nix is named after Nyx, the ancient Greek goddess personifying night. In Roman mythology she’s known as Nox. The Latin word for night, nox, appears in such words as nocturnal, equinox (equal day and night) and noctambulation (sleepwalking).

  

Kerberos: Cerberus is already the name of an asteroid, 1865 Cerberus, but the Greek form of the name, Kerberos, was acceptable to the International Astronomical Union, which does the naming. Cerberus was the three-headed dog that guarded the entrance to Hades, the infernal region in classical mythology. Ancient Greeks and Romans used to put a slice of cake in the hands of their dead to help pacify Cerberus on the way. This custom gave rise to the idiom “to give a sop to Cerberus” meaning to give a bribe to quiet a troublesome person.
Cancerbero (from Spanish can: dog) is one of the Spanish terms for a goalkeeper in soccer. Kerberos is the name given to an authentication protocol for computer networks. Cerberus is a noun meaning: A powerful, hostile guard.
 

Hydra is named after the nine-headed monster Hydra in Greek mythology. When its one head was cut off, it sprouted two more. It was ultimately slain by Hercules as the second of his Twelve Labours. Its lair was the lake of Lerna. Beneath the waters was an entrance to the Underworld, and the Hydra was its guardian. From Latin Hydra, from Greek Hudra (water snake). In language it is a noun: A persistent or multifaceted problem that presents a new obstacle when a part of it is solved.