What does "alms" mean?

Alms: Alms are but the vehicles of prayer. Dryden. Tenure by free alms. See Frankalmoign. Blackstone. Note: This word alms is singular in its form (almesse), and is sometimes so used; as, "asked an alms." Acts iii. 3."Received an alms." Shak. It is now, however, commonly a collective or plural noun. It is much used in composition, as almsgiver, almsgiving, alms bag, alms chest, etc.