(griz′əl) v.t. & v.i. griz·zled, griz·zling
To become or cause to become gray. [<adj.]
—noun
1. A mixture of white and black; gray.
2. A gray wig.
3. Obs. A gray-haired person.
—adjective Gray. [<OF grisel <gris gray]
—griz′zled adjective

(griz′əl) v.i. griz·zled, griz·zling Brit. Colloq.
To grumble or fret continuously. [Freq. of dial. E grize grind the teeth]