Substance

Essence; the material or necessary component of something.

A matter of substance, as distinguished from a matter of form, with respect to pleadings, affidavits, indictments, and other legal instruments, entails the essential sufficiency, validity, or merits of the instrument, as opposed to its method or style.

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SUBSTANCE, evidence. That which is essential; it is used in opposition to form.
     2. It is a general rule, that on any issue it is sufficient to prove the substance of the issue. For example, in a case where the defendant pleaded payment of the principal sum and all interest due, and it appeared in evidence that a gross sum was paid, not amounting to the full interest, but accepted by the plaintiff as full payment, the proof was held to be sufficient. 2 Str. 690; 1 Phil. Ev. 161.