When you need to choose between alternate and alternative, it’s easy to get confused. The words can sometimes—but not always—be synonyms.
Both words are commonly used to describe a choice among options, as in an alternate schedule or an alternative approach.
But some usage experts recommend observing the following distinction: choose alternate to mean taking turns or one thing succeeding another by turns, and choose alternative to mean offering a choice or an option.
The following examples use alternate to mean taking turns or happening by turns, one and then the other.
The band practices on alternate Fridays.
Tamika chose a pattern that alternates green and black stripes.
Alternative is not often used in the sense of taking turns, at least not in American English usage (“‘Alternate’ vs. ‘Alternative'”).
However, alternate is frequently used as a synonym of alternative, to mean a choice or an option.
They chose an alternate route because of the traffic.
The authors used an alternate method in their second study of the data.
While this usage of alternate is common enough, some would argue that alternative is better suited to express a choice. And for some kinds of choices or options, in particular to express a less typical or less mainstream choice, alternative is usually the preferred term.
Their daughter attends an alternative school that emphasizes nongraded learning.
He sought an alternative treatment for depression.
So while the meanings and usage of alternate and alternative can be interchangeable, there are indeed times when they are not. You wouldn’t say, for example, that you go jogging on “alternative weekdays” or that you listen to “alternate music.”
And in some situations not observing the distinction in meaning can lead to ambiguity (Cook 165). If you say, “We could alternately go to Vancouver and Seattle,” are you proposing alternating between Vancouver and Seattle, or are you proposing a trip to Vancouver and Seattle as an alternative to, say, a trip to Portland? To play it safe when ambiguity may result, follow the usage experts and consider using alternate to mean succeeding by turns and alternative to express a choice.
“‘Alternate’ vs. ‘Alternative’: It’s Good to Have Choices.” Merriam-Webster, 2021, www.merriam-webster.com/words-at-play/differences-between-alternate-and-alternative.
Cook, Claire Kehrwald. Line by Line: How to Improve Your Own Writing. Houghton Mifflin, 1985.