Webster’s Revised Unabridged Dictionary · 1913
Jackaroo
Jack′a·roo′, n. Also Jack′e·roo′. [Jack + kangaroo.] A young man living as an apprentice on a sheep station, or otherwise engaged in acquainting himself with colonial life. [Colloq., Australia]
Jack′a·roo′, v. i. To be a jackaroo; to pass one's time as a jackaroo. [Colloq., Australia]