Synonyms of foolproof
- 1 Syllable
- sure, tried
- 2 Syllables
- tested, sure-fire, certain, faultless, perfect, goofproof, flawless, safe
- 3 Syllables
- reliable, fail-safe, failsafe, defectless, inerrant, unfailing, idiot-proof, guaranteed, unflawed, unerring
- 4 Syllables
- infallible, inerrable, never-failing, apodictic, dependable, user-friendly
- 5 Syllables
- indefectible, undeceivable, unassailable