Being or succeeding by turns; one following the other in succession of time or place; by turns first one and then the other; hence, reciprocal.(adjective)
source: webster1913
noun (n)
someone who takes the place of another person(noun.person)
To perform by turns, or in succession; to cause to succeed by turns; to interchange regularly.(verb)
source: webster1913
To happen, succeed, or act by turns; to follow reciprocally in place or time; -- followed by with; as, the flood and ebb tides alternate with each other.(verb)