-  Grid is simply an abbreviated version of gridiron . This in turn seems to have been an alteration (through association with iron) of griddle , which is traceable back via Old French gridil to a hypothetical Vulgar Latin *crāticulum, a diminutive form of Latin crātis ‘wickerwork, hurdle’ (from which English gets grate). A parallel feminine Vulgar Latin derivative, crāticula, produced English grill  and grille . => GRATE, GRIDDLE, GRILL
The Hutchinson dictionary of word origins. 2013.