Prick up one’s ears

What is Prick up one’s ears?

Prick up one’s ears definition and meaning on Dictionary terms:
noun

a puncture made by a needle, thorn, or the like.
a sharp point; prickle.
the act of pricking: the prick of a needle.
the state or sensation of being pricked.
a sharp pain caused by or as if by being pricked; twinge.
the pointed end of a prickspur.
Slang: Vulgar.

  1. penis.
  2. an obnoxious or contemptible person.
Archaic. a goad for oxen.
Obsolete. a small or minute mark, a dot, or a point.
Obsolete. any pointed instrument or weapon.