Either

One of the most-abused words in modern American English is either. In electronics and computer programming, either is used correctly: a circuit or program says "yes" when either one switch or another switch is triggered. Somehow, too many people gained the impression that either means both. It does not, but too many people use it that way. Ex.: "I have two doghouses. I want you to paint either doghouse." A person saying this who wants doghouse #1 and doghouse #2 painted, is using English incorrectly. He should say, "I have two doghouses. I want you to paint both."

This probably evolved from mistaken assumptions. If a manager says to two workers, "You two. Grab either side of that box and carry it into the office." Each employee grabs one of two opposing sides; neither employee grabs both opposing sides, but both sides are nonetheless grabbed between them. The employees think, "Oh, okay. Either means both." Wrong! Yet this is probably how the mistake entered the English language.

When I say, you can use either one word or the other, I am saying, you can use one of the two at any one time, but not both at the same time. This is an important distinction.