adj. Having a planar diagram whose crossings alternate between "over" and "under" as one travels along the knot.
adj. Having terms that alternate between positive and negative.
The Century Dictionary and Cyclopedia
Specifically, in electricity, periodicaliy reversing or changing the direction in such a manner that the total effect in one direction is the same as in the opposite direction.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
adj. (of a current) reversing direction
adj. occurring by turns; first one and then the other
Word Usage
"Now featured below, their poem "Apple Jack Tangles the Maidy Lac with a Red, Red Ribbon" was written in alternating voices."