Source : Webster's Revised Unabridged Dictionary (1913)

Grit \Grit\, v. t. [imp. & p. p. {Gritted}; p. pr. &, vb. n.
   {Gritting}.]
   To grind; to rub harshly together; to grate; as, to grit the
   teeth. [Collog.]

Source : WordNet®

gritting
     See {grit}

grit
     v 1: cover with a grit; "grit roads"
     2: clench together; "grit one's teeth"
     [also: {gritting}, {gritted}]

grit
     n 1: a hard coarse-grained siliceous sandstone [syn: {gritrock},
          {gritstone}]
     2: fortitude and determination; "he didn't have the guts to try
        it" [syn: {backbone}, {guts}, {moxie}, {sand}, {gumption}]
     [also: {gritting}, {gritted}]