means The power or advantage you can use to get the result you want — and, as a verb, to put that advantage to work.

from From 'lever,' the simple machine that lets a small push move a heavy load, which came through Old French 'levier' from Latin 'levare,' to raise or lighten (a cousin of 'levity' and 'elevate'). 'Leverage' first meant the literal mechanical action and force of a lever; the figurative sense — advantage, influence, borrowed power — grew from that image of a small effort moving a great weight. The financial meaning (using borrowed money to amplify gains) is a later, American-flavored extension of the same idea.