Supporting, reinforcing; (music) of or related to accompaniment
Standby, reserve or extra.
That is intended as a backup.
reinforcements
A copy of a file or record, stored separately from the original, that can be used to recover the original if it is destroyed or damaged.
A reserve or substitute.
An accumulation of material caused by a (partial) obstruction or (complete) blockage of the flow or movement of the material, or an accumulation of material that causes an overflow due to the flow being greater than the maximum possible flow.
Something which makes an act or an event unavoidable; an irresistible force; overruling power.
Greater utilitarian good; used in justification of a criminal act.
Indispensable requirements (of life).
The negation of freedom in voluntary action; the subjection of all phenomena, whether material or spiritual, to inevitable causation; necessitarianism.
The condition of being needy; desperate need; lack.
Something necessary; a requisite; something indispensable.
The quality or state of being necessary, unavoidable, or absolutely requisite.