I.
a.
1.
Dull, obtuse, pointless, edgeless.
2.
Dull-witted, dull, thick-witted, obtuse, stupid, stolid.
3.
Abrupt, bluff, plain, uncourtly, unceremonious, without formal civility.
4.
Brusk (or brusque), rough, harsh, uncourteous, ungracious, impolite, rude.
II.
v. a.
1.
Dull, make dull.
2.
Benumb, paralyze, deaden, stupefy, obtund, hebetate, make insensible, callous, or obtuse.
3.
Moderate, allay, assuage, mitigate, quiet, alleviate, soften.