mammoth jack

American  

[mam-uhth jak] / ˈmæm əθ ˈdʒæk /

noun

1. Informal.  a notably large male donkey.

2. any of various large donkey breeds, including the American mammoth donkey, a landrace bred for strength from several donkey breeds brought into America in the 18th century.

---

Etymology

Origin of mammoth jack

First recorded in 1835–40; jack ¹ ( def. ) (in the sense “male donkey, jackass”)

Example Sentences

Whisper’s Star of Rapha El, or El as he is known around the barn, is a gaited, mammoth Jack stud, with an emphasis on the mammoth.

From Washington Times