Leo is the Latin word for lion, used as a name for its direct associations with courage and boldness rather than any hidden meaning. It's a name that wears its symbolism plainly -- strength on the surface, not something to be uncovered through etymology.
If Jupiter in the revolution of the world shall be in his house, exaltation, or oriental in an angle, and otherwise freed from evil, he signifies plenty, [my author says penury, if time and ill handling have not abused him] of all things. - William Lilly (1602.-1681.)