angular
angulate
many-sided
multilateral
cuneate
cuneated
cuneiform
deltoid
fan-shaped
oxygonal
three
three-cornered
three-dimensional
three-footed
three-in-one
three-pronged
three-sided
triadic
trial
triangulate
triarch
trichotomous
tricorn
tricornered
tricuspid
trident
tridental
trifid
triflorate
triflorous
trifurcate
trigonal
trigonoid
trigrammatic
trihedral
trilateral
trimerous
trinal
trine
triparted
tripartite
triple
triplex
tripodic
triquetral
triquetrous
trisected
triune
triangle
bony
conical
cylindrical
hexagonal
horizontal
jagged
rectangular
rocky
semicircular
shiny
upper
wooden
equiangular