Definition: Achilles is an ancient term referring to a person with a long, narrow, thin leg (like a snake's) and a thick, hard exoskeleton (like a horse). In Greek mythology, Achilles was the son of Hector, the king of Sparta. He became a hero after defeating his father in battle. The word "achilles" comes from his name: Achis means "son of Achilles." The exact definition of the word "achilles" can vary depending on who is using it. For example: - In Greek mythology, Achilles was the king of Sparta and the son of Hector. - In classical Roman history, a character with this name was described as having thick legs and a strong exoskeleton. It's important to note that the exact meaning and usage of "achilles" can change over time as myths and legends evolved.