Is the letter O a word?

The letter "O" is not a word in the English language. It's a single letter, not a combination of letters that forms a meaningful unit.

However, it's important to note that in some cases, "O" can be used as a word:

* As an interjection: "O, the pain!"

* As a symbol: "O" can represent zero or the letter itself.

* In specific contexts: In some languages, "O" might be a word.

So, while "O" isn't a standard English word, it can have specific meanings depending on the context.