Alternately

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

We spent most of season three alternately fascinated and horrified by the secrets of Woodbury and its leader, the Governor.
A Primer For ‘The Walking Dead’ Season Four Premiere Melissa Leon October 10, 2013

Forbes magazine has alternately called Hanauer insane and ignorant.
The Big, Long, 30-Year Conservative Lie Monica Potts August 7, 2014

Gates describes that she “alternately looked like she had swallowed an entire lemon and like she was simply going to explode.”
Speed Read: Juiciest Bits From Secretary of Defense Bob Gates’ ‘Duty’ William O’Connor January 7, 2014

alternately, Americans Elect could deny Republicans enough crossover votes to come within shouting distance of the White House.
The Web’s Stealth Presidential Race John Avlon July 22, 2011

alternately, LeBron could keep Gibson, and start at around $17.8 million.
Where Free Agent LeBron James Will Take His Talents Next Robert Silverman June 23, 2014

Historical Examples

alternately with the flour and spices, add the vanilla and fruit.
A Thousand Ways to Please a Husband Louise Bennett Weaver

The fourth row you pearl three, knit one, and pearl six, alternately.
The Ladies’ Work-Table Book Anonymous

That part of a ship lying at the surface of the water which is alternately wet and dry by the motion of the waves.
The Sailor’s Word-Book William Henry Smyth

The road was alternately rough in the valley, or over slippery ledges.
Byeways in Palestine James Finn

This society holds a general meeting yearly, in May, at Norwich and Swaffham, alternately.
A Concise History and Directory of the City of Norwich for 1811 C. Berry

adverb
in an alternating sequence or position
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
adv.

early 15c., from alternate (adj.) + -ly (2).
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.