Definition of "Alternate" :

noun: someone who takes the place of another person

verb: do something in turns

verb: go back and forth; swing back and forth between two states or conditions

verb: reverse (a direction, attitude, or course of action)

verb: be an understudy or alternate for a role

verb: exchange people temporarily to fulfill certain jobs and functions

adjective: occurring by turns; first one and then the other

adjective: every second one of a series

"The cleaning lady comes on alternate Wednesdays."

adjective: of leaves and branches etc; first on one side and then on the other in two ranks along an axis; not paired

"Stems with alternate leaves."

adjective: serving or used in place of another