That which supplies what others depend on. Named from the side of the giving.
An agent noun built on provide, from Latin providere (to foresee, to supply): pro- (ahead) + videre (to see); a provider is named for the seeing-ahead that makes the supplying possible.
That which supplies what others depend on, named from the side of the giving rather than the receiving. To provide well is to have anticipated the need before it became urgent.