Webster's Revised Unabridged Dictionary · 1913

Jackaroo

Jackaroo , noun

[Jack + kangaroo.]

A young man living as an apprentice on a sheep station, or otherwise engaged in acquainting himself with colonial life. [Colloquial, Australia]

Also: Jackeroo

Jackaroo , intransitive verb

To be a jackaroo; to pass one's time as a jackaroo. [Colloquial, Australia]