The Collaborative International Dictionary of English v.0.48:

Almsgiver \Alms"giv`er\ ([add]mz"g[i^]v`[~e]r), n.
   A giver of alms.
   [1913 Webster]

WordNet (r) 3.0 (2006):

almsgiver
    n 1: a person who gives alms

Moby Thesaurus II by Grady Ward, 1.0:

43 Moby Thesaurus words for "almsgiver":
   Maecenas, Robin Hood, Santa Claus, almoner, angel, assignor,
   awarder, backer, benevolist, bestower, cheerful giver, conferrer,
   consignor, contributor, do-gooder, donator, donor, fairy godmother,
   feoffor, financer, funder, giver, grantor, humanitarian, imparter,
   lady bountiful, patron, patroness, philanthropist, power for good,
   presenter, settler, social worker, subscriber, sugar daddy,
   supporter, testate, testator, testatrix, vouchsafer,
   welfare statist, welfare worker, well-doer