A pregnant pause/silence British American slang
A pregnant pause is a comic timing technique used to accentuate a comedy element, where the comic pauses to build up suspense at the end of a sentence. It's often used to build up a comeback at the end of a comically awkward statement or in the silence after a seemingly non-comic phrase. The pregnant pause, refined by Jack Benny, has become a staple of stand-up comedy.
A pause/silence in which everyone waits or listens for something, or a moment of silence which is full of meaning.
There was a pregnant pause while she was telling everyone about her life.
During his speech, he stopped many times due to pregnant pauses.
Used to describe a situation when people say nothing and feel worried, embarrassed or uncomfortable
Not sound, or a spoken word from someone
Used to advise people that sometimes it is better to not say anything
It is a metaphor. In that they are filled with meaning, as a pregnant body is filled with the offspring to be born, some pauses resemble literal pregnancies; and they are forward-looking, that is, they have the listener waiting for the next utterance, in something of the same way that a pregnancy carries the forthcoming birth. The Oxford English Dictionary gives examples beginning in the 15th century of the word "pregnant" used with the sense of "full of meaning".
To punish someone or something harshly
He's a really strict teacher, so he'll definitely lower the boom on you if you don't do your homework.