Synonyms of 'foolproof'

adaptable, airtight, bombproof, bulletproof, burglarproof, certain, convenient, dampproof, dependable, ductile, feasible, fireproof, flameproof, flexible, Handy, hermetic, holeproof, infallible, malleable, manageable, pliable, pliant, practical, proof, reliable, rustproof, safe, shatterproof, shellproof, soundproof, sure, sure-fire, tight, tractable, trustworthy, unfailing, watertight, weatherproof, wieldy, yielding