n.
Pronunciation: ' let- ˌ dau ̇ n
Function: noun
Date: 1768
1 a : DISCOURAGEMENT , DISAPPOINTMENT <his latest novel is a letdown > b : a slackening of effort : RELAXATION
2 : the descent of an aircraft or spacecraft to the point at which a landing approach is begun
3 : a physiological response of a lactating mammal to suckling and allied stimuli whereby previously secreted milk from the acini is expelled into ducts and drawn through the nipple