a hand held by a declarer that is or can be played with all cards exposed because no action by the opponents can prevent the declarer from taking the number of tricks necessary to make the contract.
an unbeatable contract that can so easily be made that a declarer can or does play the hand with all cards exposed.
Origin of laydown
First recorded in 1905–10; noun use of verb phrase lay down
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019