foolproof

1. Not liable to failure (synset 300968365)
   "a foolproof identification system"; "the unfailing sign of an amateur"; "an unfailing test"
   similar to: infallible - incapable of failure or error
   same as: unfailing

1. Proof against human misuse or error (synset 200166401)
   "foolproof this appliance"
   is a type of: proof - make resistant (to harm)
   same as: goof-proof, goofproof

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