jsorex> Yes, that would be a carboxylic acid.
An ester is an carboxylic acid bound to an alchohol with and condensation reaction(ie. you loose a molecule of water).
Thus an ester looks like the following
R-(C=O)-O-R
Which has been formed via. the following two molecules:
R-(C=O)-OH + HO-R + (H+) -----> R-(C=O)-O-R + H2O + (H+)
This reaction is called a Fischer esterfication, and is acid catalysed.
It is the -OH group from the carboxyl acid, that get's knocked off.
But there are several other ways of forming esters.
Check out:
http://www.people.virginia.edu/~fac6q/19_13_17.pdf
for more details!
Regards
Bandil