See this is why science drives me crazy:
Triploid = (three sets; 3x) Makes sense tri as in tripod, triangle.
Tetraploid = (four sets; 4x) Tetra??? What? Why not quadraploid?
Pentaploid = (five sets; 5x) Got it. As in Pentagram (leave pentagrams alone, according to all of the movies I've watched messing with pentagrams can be dangerous stuff).
Hexaploid = (six sets; 6x) Sure as in hexagram.
Octaploid = (eight sets; 8x) Of course, behold the Octopus
Decaploid = (ten sets; 10x) Yep as in Decade.
Dodecaploid (twelve sets; 12x) WHAT? Why not Dozenaploid?