Thruples can be defined best as a three way relationship that truly is what it sounds like it is. Thruples should be composed of at least one person that is not the same sex as the other two in the relationship. Thruples are very serious matters to those that are in them. People that are in thruples are you lovers, your best friends, and your family. Thruples are just like a couple but with three people.
Alex: "Hey man, can I come over?"
Josh: "Sorry bro, it's thruple night with my thruple mates."
Alex: "So, what's your point?"
Josh: "I have to spend time with my boyfriend and girlfriend."