This is not the place for me to go into debates about the understanding and usage of terms. Therefore, these links will direct you to more information when suitable! This list will expand as questions are received, or complicated terms arise.
Polyamory (for other Canadians that want, like I do, to spell it polyamoury – do it. Unfortunately the word is of U.S. English origin, wherein the spelling polyamory is unfortunately correct).
Triad/Trigamy/Trio – a relationship of three individuals. This may consist of any combination of genders, i.e. 3 men/women, 1 woman + 2 men, 1 man + 2 women, and including combinations those who may not prefer/identify with a gender.