Alternate

1. n. A proportion derived from another proportion by interchanging the means.
2. 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.
3. 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.
4. a. Distributed, as leaves, singly at different heights of the stem, and at equal intervals as respects angular divergence.
5. n. That which alternates with something else; vicissitude.
6. n. A substitute; one designated to take the place of another, if necessary, in performing some duty.

The word meanings were obtained from OPTED(The Online Plain Text English Dictionary), which is based on “The Project Gutenberg Etext of Webster’s Unabridged Dictionary” which is in turn based on the 1913 US Webster’s Unabridged Dictionary (See Project Gutenburg), as a text file.