s, o, e, k, n, p, h, m, t, u are letters that make 'keep one's mouth shut'
keep, mouth, hut, keep on, ut, EE, out, one, on, shut, MO, NE, Mo, Ne, Th, UT, mo are words within 'keep one's mouth shut'
1 possible definitions for 'keep one's mouth shut'
Under this definition, keep one's mouth shut is a verb and has the following properties:
keep quiet, shut one's mouth have the same meaning as 'keep one's mouth shut'
spill the beans, let the cat out of the bag, blab, babble, sing, babble out, peach, tattle, talk, blab out have the opposite meaning of 'keep one's mouth shut'