Definition of roach mane in US English:

roach mane

noun

US
  • A horse's mane that is cut short so that it stands up in a curve or roach.

Origin

Late 18th century; earliest use found in Royal Georgia Gazette. Apparently from roach + mane.

Pronunciation

roach mane

/ˈrəʊtʃ ˌmeɪn/