alternate

verb (used without object), al·ter·nat·ed, al·ter·nat·ing.

1. to interchange repeatedly and regularly with one another in time or place; rotate (usually followed by with): Day alternates with night.
2. to change back and forth between conditions, states, actions, etc.: He alternates between hope and despair.
3. to take turns: My sister and I alternated in doing the dishes.
4. Electricity. to reverse direction or sign periodically.
5. Linguistics. to occur as a variant in alternation with another form.

verb (used with object), al·ter·nat·ed, al·ter·nat·ing.

6. to perform or do in succession or one after another: to alternate comedy acts; to alternate jogging and walking.
7. to interchange successively or regularly: to alternate hot and cold compresses.

adjective

8. being in a constant state of succession or rotation; interchanged repeatedly one for another: Winter and summer are alternate seasons.
9. reciprocal; mutual: alternate acts of kindness.
10. every second one of a series: Read only the alternate lines.
11. constituting an alternative: The alternate route is more scenic.
12. alternative(defs 4, 6).
13. Botany.
    1. placed singly at different heights on the axis, on each side in succession, or at definite angular distances from one another, as leaves.
    2. opposite to the intervals between other organs: petals alternate with sepals.

noun

14. a person authorized to fill the position, exercise the duties, etc., of another who is temporarily absent; substitute.
15. Theater.
    1. either of two actors who take turns playing the same role.
    2. an understudy.
16. alternative.

verb (ˈɔːltəˌneɪt)

1. (often foll by with) to occur or cause to occur successively or by turnsday and night alternate
2. (intr often foll by between) to swing repeatedly from one condition, action, etc, to anotherhe alternates between success and failure
3. (tr) to interchange regularly or in succession
4. (intr) (of an electric current, voltage, etc) to reverse direction or sign at regular intervals, usually sinusoidally, the instantaneous value varying continuously
5. (intr often foll by for) theatre to understudy another actor or actress

adjective (ɔːlˈtɜːnɪt)

6. occurring by turnsalternate feelings of love and hate
7. every other or second one of a serieshe came to work on alternate days
8. being a second or further choice; alternativealternate director
9. botany
   1. (of leaves, flowers, etc) arranged singly at different heights on either side of the stem
   2. (of parts of a flower) arranged opposite the spaces between other partsCompare opposite (def. 4)

noun (ˈɔːltənɪt, ɔːlˈtɜːnɪt)

10. US and Canadian a person who substitutes for another in his absence; stand-in

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.

1. Arranged singly at intervals on a stem or twig. Elms, birches, oaks, cherry trees, and hickory trees have alternate leaves. Compare opposite.
2. Arranged regularly between other parts, as stamens between petals on a flower.