Three jets of particles from an event or source(noun)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "trijet" in a sentence
"A SAA Boeing 727 trijet - the Letaba - piloted by Capt Blake"
"Tuesday evening is trijet freighter evening at Manchester."
"Launched with orders from Eastern Air Lines and British Airways in 1978, the Boeing 757 was intended to replace the previous narrow-body 727 trijet on short and medium routes."