Monovalent rhymes with:
tetravalent, divalent, tetravalent, assailant, divalent, inhalant, tetravalent, ambivalent, assailant, benevolent, bulent, coolant, corpulant, divalent, equivalent, esculent, excellent, flatulent, fraudulent, galant, gallant, indolent, inhalant, insolent, jubilant, malevolent, nonviolent, opulent, petulant, pilant, prevalent, propellant, purulent, redolent, repellent, salant, sealant, silent, somnolent, stimulant, talent, tallant, tallent, tetravalent, truculent, turbulent, vigilant, violent, virulent, water-repellent, wendlandt