Horses don't just whinny and neigh — they also nicker. The horse you've been visiting with carrots every afternoon might nicker softly when she sees you coming.
The word nicker comes from Scottish and North England dialect. Horse experts will tell you that while a neigh is usually louder, often a call to people or other horses, a nicker is a softer sound, more of a vibration of the vocal cords. Mares nicker gently at their new foals, and many horses nicker at their favorite humans.