Parent or guardian

• Silver, for example, in the opening to TV's "The Lone Ranger"
• Nanny, for one
• One bringing up children behind the Queen
• Parent or scared horse
• Mom or dad, traditionally
• Skittish steed
• Parent, e.g
• Frightened horse

Wiktionary Word definitions in Wiktionary
n. 1 One who rear#Verb (gloss: nurtures children or animals). 2 A horse or other animal that rears up.

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Rearer \Rear"er\ (r[=e]r"[~e]r), n. One who, or that which, rears.