numskulled

dull simple thick

blockheaded boorish doltish dumb fatheaded ignorant imbecilic impassive lethargic oafish obtuse phlegmatic slow-witted sluggish stolid torpid

intelligent smart

brainy

boring dim dumb simple slow sluggish stupid

addled low shallow

backward besotted brainless daffy daft dense dim-witted doltish feeble-minded half-baked ignorant imbecilic indolent insensate moronic not bright obtuse scatterbrained simple-minded stolid thick unintellectual vacuous wearisome witless

active bright cognizant exciting intelligent interesting smart

clear eventful keen knifelike light lively luminous lustrous pointed quick sensitive serrated sharp vivacious witty