def. “a silent or motionless group of people arranged to represent a scene or incident”
Those who have read Jane Eyre might recall the odd form of charades described midway through. In Charlotte Brönte’s version, participants dressed up and arranged themselves in a static position to provide clues for their audience. As with charades, the point was to guess what idea or narrative was being pantomimed.
Tableaux vivants hold an interesting place in the discussion of pornography. Early in the twentieth century, having nude people hold a position was a way of getting around indecency laws. As the reasoning seems to have gone, eroticism is in the eye of the beholder. If you have an audience trained to see nudes in paintings as art rather than titillation, then to have an unclothed person hold still would be artistic rather than erotic. As long as they didn’t move, everything was okay. This will sound quite familiar to anyone who has seen Mrs. Henderson Presents (starring Judi Dench). Terry Pratchett’s Thief of Time also refers to this historical irrationality.
Olga Desmond’s Evenings of Beauty (Schönheitsabende) provide another historical example. The art form continues, and is explained rather clearly on the New Orleans Society Tableau Vivant website.
Two related concepts are those of living statues and the photographic tableau. Chan-hyo Bae is a photographer who used the latter concept to address persistent Western preconceptions that Korean men are feminine.
(If that concept doesn’t make a lot of sense, consult the Eatyourkimchi v-log “Korea Will Change You” starting about 3:40.)
Note the theatricality which characterizes all these examples.
I’d be inclined to call Duchamp’s Etant Donnes a related sort of project.