fool·proof 
(flprf′)
(flprf′)adj.
1. Designed so as to be impervious to human incompetence, error, or misuse: a foolproof detonator; a foolproof safety lock.
2. Effective; infallible: a foolproof scheme.
- perimorphism
- perimorphous
- perimysium
- perinatal
- perinatally
- perinatology
- perineal
- perinephral
- perinephrial
- perinephric
- perinephrium
- perineum
- perineurial
- perineurium
- period
- periodic
- periodic acid
- periodical
- periodical cicada
- periodically
- periodic attractor
- periodicity
- periodic law
- periodic motion
- periodic sentence