When looking for synonym options for the word "triplex", there are a few possibilities to choose from. One option is "triple", which means three times as much or threefold. Another possibility is "triune", which refers to something consisting of three parts. "Triple-decker" is another option, which means a building or object that has three levels or layers. "Triple-play" is a term used in sports, referring to a single player achieving three different events in a game. Lastly, "three-in-one" is a phrase that could be used as a synonym for "triplex", meaning something that has three different functions or purposes.