Difference between “commentor” and “commentator”

Question

What is the difference between commentor and commentator? Is commentor or commenter a legitimate English word?

Answer 1

One difference is that as far as Merriam-Webster is concerned, the word "commentor" does not even exist. Same goes for "commenter".

Edit:

Now that this has sparked some discussion, I feel like I have to expand on it.

I do see the word "commenter" (but not "commentor") being used on Reddit, blogs, or actually right here on StackExchange sites. Ex-user points out in his answer that it seems to be an online thing, and I agree with him on that.

However, I think that Ex-user is not entirely right that "commentator" sounds like someone who comments on sports. There are, for example, political commentators. Everyone is familiar with them, these guys are all over the news networks 24/7, but they usually don't comment on sports.

Back to Merriam-Webster, my understanding is that they are usually not too slow to catch up with the latest trends. They have a special section "New Words & Slang", a collection of user-submitted words. There you can find, for example, not one but five proposed meanings of the verb "to facebook". However, even that dedicated section doesn't mention "commenter", although blogs and online forums predate Facebook.

All that being said, there is no question that morphologically, "commenter" makes perfect sense. A killer is someone who kills, a driver is someone who drives, and a commenter is someone who comments. The "-er" is a so-called agent noun suffix, and it is very common in English.

On the other hand, the agent noun suffix "-or", while it does exist, is not common at all. Wiktionary lists as few as twelve terms that were derived using this suffix, and offers the following usage notes:

English generally appends this suffix where Latin would do it—to the root of a Latin-type perfect passive participle. For other words, English tends to use the suffix -er. Occasionally both are used (computer vs. computor).

Depending on where you live, you may have never encountered the word "computor" at all. However, I bet you have seen the word "computer" many times.

The bottom line:

1. The word "commenter" is pretty common online, so if you use it, people should understand you. In formal writing, you might wish to use "commentator" instead.
   
   
2. If you want to be on the safe side, you probably should not use "commentor" at all, though nobody can forbid you to do so.

Of course, the English language is constantly evolving, so both of the above recommendations may become obsolete as time passes.

Answer 2

The New Oxford American Dictionary reports that the meaning of commentator is

commentator |ˈkɑmənˌteɪdər|
noun
A person who comments on events, esp. on television or radio.
• A person who writes a commentary on a text.

For commenter, it reports only that it is a noun.

The Corpus of Contemporary American English reports that commenter has been used between 2005–2010 more than the previous years (a ratio of 10:1). The word is used more on newspapers, and magazines, where it is used in sentences like

There is no humanity reading a book on a computer," wrote an anonymous commenter on the popular site ParentDish.com.

Even in academic context, the word is used with reference to who comments on a website.

[…] a school-board member in his home state of Nevada, from Charles Krauthammer to a commenter on a blog or a caller to a radio show.

Answer 3

A commentator is someone who commentates. A commenter is someone who comments.

A commentary would consist of many comments, normally as an event unfolds (be it sports, political, etc.) It would also be valid to have a commentary on a written text which may be explanatory notes, etc.

Answer 4

My own feeling about this is that "commenter" is a new word used to mean the people who make comments on internet blogs or forums etc. If you say someone is a "commentator" it sounds like they are the person who comments on sports games as you watch them on the television, hence the necessity for the new word. However, strictly speaking, the person who writes comments on blogs is actually a "commentator".

Answer 5

The OED’s entry for ‘commenter / ’commentor’, in the sense ‘one who comments; a commentator’, describes it as obsolete, but that clearly takes no account of its use on the internet. It isn’t new. The earliest citation is some time before 1387 and there are subsequent citations from Donne and Coleridge.

Answer 6

A commentator commentates events (like sport games on radio and TV) according to attributed time slot. That's why he has to fill with words the pauses in games, events, etc.

A commenter, on the contrary, comments. He is not obliged to maintain a word flow. Even more, he would be most probably banned as spammer for for commenting in order to fill the gaps in conversation.