Presumptuous (adjective)

1. Excessively forward or bold; assuming too much.
2. Exhibiting an attitude of superiority or self-importance.

Origin:

Late middle english (in the sense "taking liberties, overstepping the mark"): from old french presomptueux, from latin praesumptuosus, from praesumere "take for granted", from prae "before" + sumere "take".

Examples:

1. It was presumptuous of him to assume that he would be invited to the party without being asked.
2. It was a bit presumptuous of me to assume that I knew what she wanted before she had even said anything.
3. She thought it was presumptuous of him to assume that she would be happy to see him again.
4. He felt that it would be presumptuous of him to ask for a promotion after only a few months on the job.
5. It was a bit presumptuous of her to assume that she knew what was best for the company without consulting anyone else.