rely (v.)

early 14c., "to gather, assemble" (transitive and intransitive), from Old French relier "assemble, put together; fasten, attach, rally, oblige," from Latin religare "fasten, bind fast," from re-, intensive prefix (see re-), + ligare "to bind" (from PIE root *leig- "to tie, bind"). Sense of "depend, trust" is from 1570s, perhaps via notion of "rally to, fall back on." Typically used with on, perhaps by influence of lie (v.2). Related: Relied; relying.