Alternating

to interchange repeatedly and regularly with one another in time or place; rotate (usually followed by with):
Day alternates with night.
to change back and forth between conditions, states, actions, etc.:
He alternates between hope and despair.
to take turns:
My sister and I alternated in doing the dishes.
Electricity. to reverse direction or sign periodically.
Linguistics. to occur as a variant in with another form.
to perform or do in succession or one after another:
to alternate comedy acts; to alternate jogging and walking.
to interchange successively or regularly:
to alternate hot and cold compresses.
being in a constant state of succession or rotation; interchanged repeatedly one for another:
Winter and summer are alternate seasons.
reciprocal; mutual:
alternate acts of kindness.
every second one of a series:
Read only the alternate lines.
constituting an alternative:
The alternate route is more scenic.
(defs 4, 6).
Botany.

placed singly at different heights on the axis, on each side in succession, or at definite angular distances from one another, as leaves.
opposite to the intervals between other organs:
petals alternate with sepals.

a person authorized to fill the position, exercise the duties, etc., of another who is temporarily absent; substitute.
Theater.

either of two actors who take turns playing the same role.
an understudy.

.
Contemporary Examples

I quickly became the “weirdo mommy” at Gymboree, alternating between speed talking, accidental swearing, and thousand-yard stares.
My Real-Life ‘Suburgatory’ Linda Erin Keenan September 27, 2011

In alternating scenes, the audience watches both the scholar’s theory—and the 19th-century reality—unfolding.
The Past Is Present in Arcadia Janice Kaplan March 15, 2011

Complete three sets of 10 to 12 reps on each side, alternating legs, moving forward with a step in between each kick.
5 Exercises to Get Ski and Snowboard Ready DailyBurn January 1, 2014

He had spent nearly 20 years covering politics in the Bay State, alternating between the Associated Press and the Boston Globe.
From Rick Stengel to David Axelrod, All of the President’s Journalists Ben Jacobs September 12, 2013

She told the court Galliano called her “Jewish,” with an alternating cast of R-rated words attached, “at least 30 times.”
John Galliano in the Courtroom Tracy McNicoll June 22, 2011

Historical Examples

On fine mornings he used to spend two or three hours on the Serpentine, alternating rowing and dictating.
Herbert Spencer J. Arthur Thomson

The peppermints were arranged in a row, a red one and a striped one alternating.
Cricket at the Seashore Elizabeth Westyn Timlow

With alternating currents, the rods are equally consumed and produce equal amounts of light.
Physics Willis Eugene Tower

alternating with these warlike scenes were the family portraits.
The Dead Command Vicente Blasco Ibez

Sliced bananas, lightly sprinkled with sugar, alternating in layers with sections of oranges, make a most delicious dessert.
Science in the Kitchen. Mrs. E. E. Kellogg

verb (ˈɔːltəˌneɪt)
(often foll by with) to occur or cause to occur successively or by turns: day and night alternate
(intransitive) often foll by between. to swing repeatedly from one condition, action, etc, to another: he alternates between success and failure
(transitive) to interchange regularly or in succession
(intransitive) (of an electric current, voltage, etc) to reverse direction or sign at regular intervals, usually sinusoidally, the instantaneous value varying continuously
(theatre) (intransitive) often foll by for. to understudy another actor or actress
adjective (ɔːlˈtɜːnɪt)
occurring by turns: alternate feelings of love and hate
every other or second one of a series: he came to work on alternate days
being a second or further choice; alternative: alternate director
(botany)

(of leaves, flowers, etc) arranged singly at different heights on either side of the stem
(of parts of a flower) arranged opposite the spaces between other parts Compare opposite (sense 4)

noun (ˈɔːltənɪt; ɔːlˈtɜːnɪt)
(US & Canadian) a person who substitutes for another in his absence; stand-in
adj.

1550s, present participle adjective from alternate (v.). Alternating current is recorded from 1839.
adj.

1510s, from Latin alternatus “one after the other,” past participle of alternare “to do first one thing then the other; exchange parts,” from alternus “one after the other, alternate, in turns, reciprocal,” from alter “the other” (see alter). Alternate means “by turns;” alternative means “offering a choice.” Both imply two kinds or things.
v.

1590s, from Latin alternatus, past participle of alternare (see alternate (adj.)). Replaced Middle English alternen “to vary, alternate” (early 15c.). Related: Alternated; alternating.
n.

1718, “that which alternates (with anything else),” from alternate (adj.). Meaning “a substitute” is first attested 1848.
alternate
(ôl’tər-nĭt)

Arranged singly at intervals on a stem or twig. Elms, birches, oaks, cherry trees, and hickory trees have alternate leaves. Compare opposite.

Arranged regularly between other parts, as stamens between petals on a flower.