Do you know ghouls from goblins and ghosts?
late 13c., from Old French grapil "hook" (see grapnel). The verb is 1520s, "seize and hold fast," from the noun. Sense of "battle, struggle (with)" is from 1590s. Related: Grappled; grappling.
GRAPh Processing LanguagE. 1968. ["A Directed Graph Representation for Computer Simulation of Belief Systems", L.G. Tesler et al, Math Biosciences 2:19-40 (1968)].