sign vs. autograph
 

What does this image show? An autographed baseball, doesn't it? Do you say a "signed" baseball instead?

Re: sign vs. autograph
 

Yes, an autographed baseball. "sign" is used for documents - when you add your name to something to authenticate it, for example sign a cheque, sign your tax forms, sign a letter. "autograph" is used when someone famous gives you their signature to keep as a memento of your having met them. Of course, what you do is the same thing - write your name in your typical handwriting. - so it's also true that this baseball has been signed. But because of the purpose, "autographed" would probably be used here.

One slight exception, incidentally, is when an author signs a copy of a book s/he's written. Then we do tend to use "sign" rather than "autograph".

Re: sign vs. autograph
 

both sound fine to me but I think autographed ball is better.

However, if you do an image search for "signed ball" you get 60 million results. autographed ball comes back with 2 million.

Re: sign vs. autograph
 

you could say both but if you're looking for the most natural or common form of English, you'd say 'signed'. Native speakers will always talk about a 'signed copy' of a book (e.g. signed by the author), an 'autographed copy' sounds rather unnatural.

Re: sign vs. autograph
 

The only time I'm in a rush and don't check on Google or another concordancer :( Didn't even know there were 60m signed balls in existence...

Have to say though that I'm happy with both "signed" and "autographed" in all the contexts we've mentioned. An either/or example possibly, with differences in frequency ("signed" seems to win hands down) but with both remaining possible and dependent on idiolect -ie the tendencies of the individual speaker? It may be that "autographed" is more usual amongst older speakers ( like me I'm afraid :) ) - but that the language is changing to favour "signed"? User age is unfortunately something the concordancers don't tell us. A pity, because it has enormous relevance...

Re: sign vs. autograph
 

I'd like to add to this that asking someone for their autograph (a regular person) can also be an informal way of asking someone to sign something.

I grew up saying both but when I think of a baseball, I would generally think of signed. Mostly this is due to the movie "Sandlot"

Re: sign vs. autograph
 

Yes true....sign becomes an autograph if done on objects which one could keep as a momento.