transitive verb
1.
a. : to allow to descend gradually : lower
let the wagons down the steep slope by means of ropes snubbed around trees — G.R.Stewart
b.
(1) : to lengthen (a garment) by releasing a fold of material
let down a skirt
(2) : to reduce the amount of (a fold) so as to lengthen a garment
let a hem down
c. : to release (formed milk secretion) within the udder
2.
a. : to fail to support : desert in a moment of need : forsake , betray
peasants who had let down the revolutionary cause — Times Literary Supplement
senators felt that they had been let down by their own administration — Harry Conn
will not let each other down at the conference table any more than we did on the battlefield — R.M.Makins
b. : to fall short of the expectations of : go back on a promise to : disappoint , fail
the plot is good but the end lets you down
the White mountains wouldn't let me down — G.M.Smith
had two appointments with the crown prince and let him down on both occasions — George Mikes
sorry for the kid, and tried to let him down easy — Dorothy C. Fisher
3. : to thin out : dilute: as
a. : to reduce the intensity of (a colored pigment) by the addition of colorless pigment
b. : to reduce the viscosity of (a paint or varnish) by adding thinner
4.
a. : to put (a horse) out of action by having a sinew broken
b. : to hang low and straight — used of the posterior parts of an animal's body
the hocks are well let down
a sow well let down in the hams
c. : to reduce the weight of (an animal in show condition) : make less fat
highly fitted cattle … may have to be let down carefully to develop into useful breeders — W.A.Cochell
intransitive verb
1. : to slacken exertion or mental tension : relax
all through the crisis she never once let down
2.
a. : to bring an airplane down in a glide especially as a prelude to landing it
throttle back … until you're letting down about 200 feet a minute — J.N.Bell
b. : to come down gradually especially for a landing
the plane let down through heavy overcast — Time