The Collaborative International Dictionary of English v.0.48:

Friar \Fri"ar\, n. [OR. frere, F. fr[`e]re brother, friar, fr.
   L. frater brother. See Brother.]
   1. (R. C. Ch.) A brother or member of any religious order,
      but especially of one of the four mendicant orders, viz:
      (a) Minors, Gray Friars, or Franciscans. (b)
      Augustines. (c) Dominicans or Black Friars. (d) White
      Friars or Carmelites. See these names in the Vocabulary.
      [1913 Webster]

   2. (Print.) A white or pale patch on a printed page.
      [1913 Webster]

   3. (Zool.) An American fish; the silversides.
      [1913 Webster]

   Friar bird (Zool.), an Australian bird (Tropidorhynchus
      corniculatus), having the head destitute of feathers; --
      called also coldong, leatherhead, pimlico; poor
      soldier, and four-o'clock. The name is also applied to
      several other species of the same genus.

   Friar's balsam (Med.), a stimulating application for wounds
      and ulcers, being an alcoholic solution of benzoin,
      styrax, tolu balsam, and aloes; compound tincture of
      benzoin. --Brande & C.

   Friar's cap (Bot.), the monkshood.

   Friar's cowl (Bot.), an arumlike plant (Arisarum vulgare)
      with a spathe or involucral leaf resembling a cowl.

   Friar's lantern, the ignis fatuus or Will-o'-the-wisp.
      --Milton.

   Friar skate (Zool.), the European white or sharpnosed skate
      (Raia alba); -- called also Burton skate, border
      ray, scad, and doctor.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Silversides \Sil"ver*sides`\, n. (Zool.)
   Any one of several species of small fishes of the family
   Atherinidae, having a silvery stripe along each side of the
   body. The common species of the American coast (Menidia
   notata) is very abundant. Called also silverside, sand
   smelt, friar, tailor, and tinker.
   [1913 Webster]

   Brook silversides (Zool.), a small fresh-water North
      American fish (Labadesthes sicculus) related to the
      marine silversides.
      [1913 Webster]

WordNet (r) 3.0 (2006):

friar
    n 1: a male member of a religious order that originally relied
         solely on alms [syn: friar, mendicant]

Moby Thesaurus II by Grady Ward, 1.0:

26 Moby Thesaurus words for "friar":
   abbacomes, abbot, ascetic, beadsman, brother, caloyer, celibate,
   cenobite, conventual, conventual prior, grand prior, hermit,
   hieromonach, lay abbot, lay brother, mendicant, monastic, monk,
   palmer, pilgrim, pillar saint, pillarist, prior, religieux,
   religious, stylite