Is it ensure, insure, or assure?
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)].