troilism

noun

1. (uncountable)The practice of two people having sex while a third person watches (and may or may not take part).

   “Troilism is primarily a male problem, but one case of a woman who watched her husband have intercourse with a young girl has been reported in the literature (Smith, 1976).”

   “These various strands are frequently interwoven in Banville's many glimpses, glancing hints, and full scenes of troilism.”

   “Although historically troilism has been conceptualized as a form of voyeurism, […] in cases of troilism the sexual partners are typically aware that they are being observed.”

2. (uncountable)The practice of three people having sex, i.e. having threesomes.

   “Now if it's true, as I believe, that every woman has a bit of a lesbian streak, or at least curiosity, then it follows that the ideal way to satisfy it is with troilism — making love with two girls and a man. I've tried it myself and I know.”

   “The woman wants to censor us, Hill. If she had her way, all we'd show would be Andy bloody Pandy, and she'd stop him climbing into that basket with Looby Lou - let alone Teddy - lest some child be corrupted by the whiff of puppet troilism. And bestiality, I suppose - or would it be bestiality with a teddy bear... rather than a real bear?”