Supplemental

a.

1.

Added to supply what is wanted; additional; being, or serving as, a supplement; as, a supplemental law; a supplementary sheet or volume. Supplemental air (Physiol.) the air which in addition to the residual air remains in the lungs after ordinary expiration, but which, unlike the residual air, can be expelled; reserve air. Supplemental bill (Equity) a bill filed in aid of an original bill to supply some deffect in the latter, or to set forth new facts which can not be done by amendment. Supplementary chords (Math.) in an ellipse or hyperbola, any two chords drawn through the extremities of a diameter, and intersecting on the curve. - Burrill.

Adj.	1.	supplemental - functioning in a subsidiary or supporting capacity; "the main library and its auxiliary branches" Synonyms: auxiliary, subsidiary, supplementary
	2.	supplemental - added to complete or make up a deficiency; "produced supplementary volumes"; "additional reading" Synonyms: supplementary, additional

SUPPLEMENTAL. That which is added to a thing to complete it as a supplemental affidavit, which is an additional affidavit to make out a case; a supplemental bill. (q.v.)

auxiliary, secondary, subsidiary, supplementary