Of an angle, lying between 90 and 180 degrees (6)
I believe the answer is:
obtuse
(Other definitions for obtuse that I've seen before include "Dense, dim about the angle" , "Thick, blunt" , "(Of angle) between 90° and 180° - dull" , "Angle greater than 90 degrees" , "(Of angle) between 90deg and 180deg - dull" .)