Definition of alternate noun from the Oxford Advanced Learner's Dictionary

BrE BrE//ˈɔːltɜːnət//
; NAmE NAmE//ˈɔːltərnət//
(North American English) a person who does a job for somebody who is away More Like This Pronunciation changes by part of speech abuse, alternate, advocate, approximate, contract, converse, convict, decrease, delegate, discount, duplicate, estimate, export, extract, graduate, import, intimate, moderate, object, permit, present, protest, record, refund, refuse, subject, suspect, survey, torment, upgradeSee worksheet.
Word Originearly 16th cent.: from Latin alternat- ‘done by turns’, from alternare, from alternus ‘every other’, from alter ‘other’.
See the Oxford Advanced American Dictionary entry: alternate