Alter vs. altar: what's the difference?

The short answer

Alter and altar sound exactly alike, but they belong to entirely different parts of speech. Alter is a verb that means to change or modify something. Altar is a noun that names a table or raised platform used for religious rites, weddings, and other ceremonies. Because they are pronounced identically, spelling is the only clue to which one a writer intends.

• Alter, a verb, means to change
• Altar, a noun, names a ceremonial platform

What each word means

To alter a document means to change its wording or content. A tailor might alter a suit so it fits better, and a company might alter its policy after customer complaints. None of these uses involve a physical object called an altar; they all describe the act of changing something.

An altar, by contrast, is a physical structure. In many religious traditions, it is the table or platform where offerings, prayers, or rituals take place. Couples are sometimes described as standing at the altar during a wedding ceremony, and a church altar is typically positioned at the front of the building.

How to tell them apart

A quick trick is to check whether your sentence describes an action or a place. If you can replace the word with change, modify, or adjust and the sentence still makes sense, you need alter. If your sentence describes a physical location or object, especially in a religious setting, you need altar. She decided to alter her travel plans, not altar.

Another helpful check is to look at the surrounding words. Verbs like will, to, or can typically sit next to alter, as in will alter, to alter, or can alter, because it is functioning as an action. Nouns like the, an, or at typically sit next to altar, as in the altar, an altar, or at the altar, because it is naming a place or an object.

Common mistakes to avoid

Because the words are homophones, spell-check often will not catch the error, since altar and alter are both valid words on their own. Not: the seamstress will altar the dress. Correct: the seamstress will alter the dress. Not: the couple exchanged vows at the alter. Correct: the couple exchanged vows at the altar.

This confusion appears often in wedding writing, where altar is essential vocabulary, and in legal or technical writing, where alter appears constantly to describe changes to contracts, terms, or designs. Proofreading each instance separately, rather than relying on a single memory rule, helps catch the error before it reaches a reader who will notice it immediately.

Remember it

Remember that alter has an e like change, edit, and revise, all verbs about modification. Altar has an a, like a church altar or a sacred place. Linking the vowel to the meaning makes the spelling easier to recall under pressure, since this small vowel difference is the only signal you have when pronunciation offers no help at all.