Designed so as to be impervious to human incompetence, error, or misuse: a foolproof detonator; a foolproof safety lock. (adjective)
Effective; infallible: a foolproof scheme. (adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "foolproof" in a sentence
"“A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools.”"
"Curse that Aimee and her so-called foolproof formula for success: “Wear your hair down and the highest heels you have, then watch the tips roll in.”"
"The little formulas that the smart boys who design these so-called foolproof systems build in so they can sneak a gander whenever they feel like it."