There is one that slippeth in his speech, but not from his heart.
Ecclus. xix. 16.
To let slip, to loose from the slip or noose, as a hound; to allow to
escape.
Cry, "Havoc," and let slip the dogs of war.
Shak.
Slip (?), v. t. 1. To cause to move smoothly and quickly; to slide; to
convey gently or secretly.
He tried to slip a powder into her drink.
Arbuthnot.