To stop talking, or to not say anything
fall silent phrase
to stop talking or making a noise
hush verb
to stop talking, crying, or making a noise, or to make someone do this
dry up phrase
to stop talking because you do not know what to say
falter verb
to stop speaking, or to speak with pauses between the words, because you are nervous or upset
clam up phrase
to suddenly stop talking or explaining something, because you are embarrassed, unhappy, or want to keep a secret
shut up phrase
to stop talking or making a noise
hold your tongue phrase
to say nothing, although you want to speak
keep your mouth shut phrase
to not say anything
bite your tongue/lip phrase
to stop yourself from saying something that might upset or annoy someone
let something drop/rest phrase
to stop talking about something