grade / grayed are similar-sounding terms with different meanings (referred to as homophones). To better understand the differences, see below for definitions, pronunciation guides, and example sentences using each term. 👇
grade: (noun) a relative position or degree of value in a graded group. (noun) the gradient of a slope or road or other surface. (noun) a degree of ablaut. (noun) the height of the ground on which something stands. (noun) a variety of cattle produced by crossbreeding with a superior breed. (verb) level to the right gradient. (verb) assign a grade or rank to, according to one's evaluation. (verb) determine the grade of or assign a grade to.
grayed: NA
grade: g·r·EY·d
grayed: NA
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)