make unnecessary, save - make unnecessary an expenditure or effort; "This will save money"; "I'll save you the trouble"; "This will save you a lot of time"

deflect, fend off, head off, avert, stave off, ward off, avoid, debar, obviate - prevent the occurrence of; prevent from happening; "Let's avoid a confrontation"; "head off a confrontation"; "avert a strike"

blockade, obstruct, stymie, stymy, embarrass, hinder, block - hinder or prevent the progress or accomplishment of; "His brother blocked him at every turn"

frustrate, queer, scotch, thwart, foil, baffle, bilk, cross, spoil - hinder or prevent (the efforts, plans, or desires) of; "What ultimately frustrated every challenger was Ruth's amazing September surge"; "foil your opponent"

kibosh, stop, block, halt - stop from happening or developing; "Block his election"; "Halt the process"

obviate, rid of, eliminate - do away with