For all intents and purposes, alternate and alternative are synonymous. Both words date to the middle of the 16th century, and both describe a choice apart from what is first offered: an alternate viewpoint; an alternative suggestion.

As an adjective, alternate means (1) happening in turns, or (2) serving in place of anothe r. Alternative means (1) providing a choice between two or more things, or (2) existing outside the mainstream. Of course, alternate also works as a verb meaning to take turns. Alternative has no verb sense.

Alternate and alternative are easy to confuse. 'Alternate' means a replacement for the original (i.e., the original is not an option). 'Alternative' means another option to the original (i.e., the original is still on option).

While "alternate" pertains to two things succeeding each other in a definite pattern, "alternative" denotes a choice among two or more possibilities. For instance, when discussing time or sequence, "alternate" refers to the act of switching between things, typically at regular intervals.

Alternate and Alternative came from the same Latin root word. Still, they have evolved to mean different things, even though they look very similar. Alternate refers to changing back and forth, while alternative refers to a choice between two or more things.