Choosing between "alter" and "altar" is really quite simple once you realize that one is a verb (alter) and the other is a noun (altar). At that point, it's just a matter of determining whether you need a noun or a verb in the context of a sentence. Let's look at the two definitions:
- Alter is a verb meaning
to make different without changing into something else
orto become different.
The only time you will see it in another context would be as an adjective (for example, "alter ego"). In that sense, it will still retain the meaning of "having changed" but be used as an adjective instead. - Altar, on the other hand, is a noun meaning
a usually raised structure or place on which sacrifices are offered or incense is burned in worship—often used figuratively to describe a thing given great or undue precedence or value especially at the cost of something else [for example, sacrificed his family life on the altar of career advancement].
As you can see, simply looking at the context of the word in the sentence will help clarify which word ("altar" vs. "alter") should be used. Here are some examples of each word used in context correctly:
Alter
- When you dye your hair, you will alter its texture.
- Don't alter that photo, we want to make sure it's the original.
Altar
- The bride and groom said their vows at an altar decorated with flowers and candles.
- The ceremony will take place at the church's altar.