intransitive verb
Etymology: let (III) + up
1.
a. : to diminish or slow down : slacken , relax
the wind's letting up a little
not one of us should let up in our drive for standardizing our procedures — H.H.Helm
free to … let up and enjoy ourselves — A.L.Rowse
b. : to become idle : cease , stop
pitched horseshoes the whole evening and never let up until it was too dark to see
took shelter under a carriage shed until the rain let up — Oliver LaFarge
2. : to ease up or become less severe — used with on
able to let up slightly on armament expeditures — D.M.Keezer
remove some of these restrictions, let up a bit on people — T.P.Whitney
let up on him — he didn't mean any harm