The Collaborative International Dictionary of English v.0.48:

Grail \Grail\, n. [F. gr[^e]le hail, from gr['e]s grit, OHG.
   griex, grioz, G. gries, gravel, grit. See Grit.]
   Small particles of earth; gravel. [Obs.]
   [1913 Webster]

         Lying down upon the sandy grail.         --Spenser.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Grail \Grail\ (gr[=a]l), n. [Cf. OF. graite slender, F.
   gr[^e]te.]
   One of the small feathers of a hawk.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Grail \Grail\, n. [OF. greel, LL. gradale. See Gradual, n.]
   A book of offices in the Roman Catholic Church; a gradual.
   [Obs.] --T. Warton.
   [1913 Webster]

         Such as antiphonals, missals, grails, processionals,
         etc.                                     --Strype.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Grail \Grail\, n. [OF. graal, greal, greet, F. graal, gr['e]al,
   LL. gradalis, gradale, prob. derived fr. L. crater bowl,
   mixing vessel, Gr. krath`r. See Crater.]
   A broad, open dish; a chalice; -- only used of the Holy
   Grail.
   [1913 Webster]

   Note: The Holy Grail, according to some legends of the Middle
         Ages, was the cup used by our Savior in dispensing the
         wine at the last supper; and according to others, the
         platter on which the paschal lamb was served at the
         last Passover observed by our Lord. This cup, according
         to the legend, if appoached by any but a perfectly pure
         and holy person, would be borne away and vanish from
         the sight. The quest of the Holy Grail was to be
         undertaken only by a knight who was perfectly chaste in
         thought, word, and act.
         [1913 Webster]

WordNet (r) 3.0 (2006):

grail
    n 1: the object of any prolonged endeavor
    2: (legend) chalice used by Christ at the Last Supper [syn:
       grail, Holy Grail, Sangraal]

The Free On-line Dictionary of Computing (30 December 2018):

GRAIL

   Graphical Input Language.

   A flow chart language entered on a graphics tablet.  The
   graphical follow-on to JOSS.

   ["The GRAIL Language and Operations", T.O. Ellis et al,
   RM-6001-ARPA, RAND, Sept 1969].

   (1995-01-23)