Clarity of Definition
First of all see whether he has used any attribute that belongs universally. For the genus ought to divide the object from things in general, and the differentia from any of the things contained in the same genus. Now any term that belongs to everything separates off the given object from absolutely nothing, while any that belongs to all the things that fall under the same genus does not separate it off from the things contained in the same genus. Any addition of that kind will be redundant.
Or see if, though the additional matter may be peculiar to the given term, yet even when it is struck out the rest of the expression too is peculiar and makes clear the essence of the term. Speaking generally, everything is superfluous upon whose removal the remainder still makes the term that is being defined clear.
A correct definition must define a thing through its genus and its differentiae, and these belong to the order of things which are absolutely more intelligible than, and prior to, the species, not simultaneous, opposite or posterior to the species.