Available Definitions:
1) a. - 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.
2) a. - Designating the members in a series, which regularly intervene between the members of another series, as the odd or even numbers of the numerals; every other; every second; as, the alternate members 1, 3, 5, 7, etc. ; read every alternate line.
3) a. - Distributed, as leaves, singly at different heights of the stem, and at equal intervals as respects angular divergence.
4) n. - That which alternates with something else; vicissitude.
5) n. - A substitute; one designated to take the place of another, if necessary, in performing some duty.
6) n. - A proportion derived from another proportion by interchanging the means.
7) v. t. - To perform by turns, or in succession; to cause to succeed by turns; to interchange regularly.
8) v. i. - 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.
9) v. i. - To vary by turns; as, the land alternates between rocky hills and sandy plains.