DEFINITION. An enumerition of the principal ideas of which a compound idea is formed, to ascertain and explain its nature and character; or it is that which denotes and points out the substance of a thing, to us. Ayliffe's Pand. 59.
2. A definition ought to contain every idea which belongs to the thing defined, and exclude all others.
3. A definition should be, 1st. Universal, that is, such that it will apply equally to all individuals of, the same kind. 2d. Proper, that is, such that it will not apply to any other individual of any other kind. 3d. Clear, that is, without any equivocal, vague, or unknown word. 4th. Short, that is, without any useless word, or any foreign to the idea intended to be defined.
4. Definitions are always dangerous, because it is always difficult to prevent their being inaccurate, or their becoming so; omnis definitio injure civili periculosa est, parum est enim, ut non subvertipossit.
5. All ideas are not susceptible of definitions, and many words cannot be defined. This inability is frequently supplied, in a considerable degree, by descriptions. (q. v.)