Defined:

Any valid argument which has premises that are true.

When analyzing an argument, there are two features which you must look at. First, determine whether or not the argument is valid. In other words, is the argument a deductive form? Second, determine whether or not the argument has premises which are true. If both criteria are met, then the argument is sound. This means there is no possible way that the conclusion can be false.

(Note: The word "cogent" means the same thing as "sound.")