Long head hair on a
mammal. Male
lions and
horses in particular have manes. Male lions have a darker fringe of hair framing their face; this is their mane. Horses have a line of long hair growing along their neck up to the top of their head; this is their mane. Manes give animals a peculiar
anthropomorphic look, because of the similarity of placement to long
human hairstyles.
My Little Pony dolls in particular
exploit this.
Mane is also used to describe long hair on a person, particularly in cheesy porn and romance novels for some reason. As in "she had a wild mane of beautiful brown tresses" or somesuch.