Question regarding copyright

[jatinpatel007]

Hello sir,  I need to know “PDF” keyword is a copyright keyword. If not can I use this keyword in android application icon?

[try67 · Accepted solution]

I'm not a lawyer, but I don't think "PDF" is copyrighted or trademarked.

I'm not even sure you could copyright a file extension in the first place. See: File extensions cannot be trademarks | Internet law blog