monkey wrench noun 2verb 2forms 4 noun2 •A wrench (spanner) with an adjustable jaw.Did you ever stop to think whether or not you knew how a monkey wrench should be used? — 1903 •(figurative) An unexpected or troublesome problem, obstacle or dilemma.Professor Miller's careful research has thrown a monkey-wrench into the Einstein wheel, although it has far from discouraged the enthusiastic exponents of Einsteinism. — 1926 verb2 •To apply a monkey wrench, e.g. to tighten or loosen nuts. •To introduce problems, to create unexpected trouble, to sabotage.I think it’s possible that [US Vice President J.D.] Vance didn’t intend to monkey wrench [the meeting with US President Donald Trump and Ukrainian President Volodymyr Zelensky]. — 2025 formsmonkey wrenched · monkey wrenching · monkey wrenches · monkey-wrenches