* STUPID *

OAF a clumsy, stupid person [n OAFS or OAVES] : OAFISH [adj], OAFISHLY [adv]

CLOD a {dolt=n} [n -S] : CLODDISH [adj] CLODDY
COOF a {dolt=n} [n -S] : CUIF
CUIF {coof=n} [n -S]
DOLT a stupid person [n -S] : DOLTISH [adj]
DOPY {dopey=adj} [adj DOPIER, DOPIEST]
DORK a stupid or foolish person [n -S]
DULL mentally slow [adj DULLER, DULLEST] / to make less sharp [v -ED, -ING, -S]
DUMB incapable of speech [adj DUMBER, DUMBEST] : DUMBLY [adv] / to make {silent=adj} [v -ED, -ING, -S]
GABY a {dolt=n} [n -BIES]
GAWK to stare stupidly [v -ED, -ING, -S]
GAWP to stare stupidly [v -ED, -ING, -S]  : GAWPER(s)
SPAZ a clumsy, foolish, or incompetent person [n SPAZZES]
YUTZ a stupid, foolish, or ineffectual person [n -ES]

BOOBY a {dolt=n} [n -BIES] : BOOBISH
CRASS grossly vulgar or stupid [adj CRASSER, CRASSEST] : CRASSLY [adv]
DOPEY lethargic; stupid [adj DOPIER, DOPIEST] : DOPILY [adv], DOPY
DORKY stupid, foolish [adj DORKIER, DORKIEST]
DUFUS {doofus=n} [n -ES]
DUMBO a stupid person [n -BOS]
DUMMY to make a representation of [v -MIED, -MYING, -MIES]
DUNCE a stupid person [n -S] : DUNCICAL, DUNCISH [adj] : BEDUNCE, 
GOONY {gooney=n} [n -NIES] / {stupid=adj} [adj GOONIER, GOONIEST] : GOONEY GOONIE GOONY
SCHMO a stupid person [n SCHMOES or SCHMOS] : SCHMOE
SHLUB {schlub=n} [n -S]

BEDUMB to render speechless [v -ED, -ING, -S]
BETISE stupidity [n -S]
CLODDY {lumpy=adj} [adj -DIER, -DIEST]
DOOFUS a stupid or foolish person [n -ES] : DUFUS
GAWPER one that {gawps=v} [n -S]
GOONEY an albatross [n -NEYS] : GOONEY GOONIE GOONY
GOONIE {gooney=n} [n -S] : GOONEY GOONIE GOONY
LURDAN a lazy or stupid person [n -S] : LURDANE(s)
NITWIT a stupid person [n -S]
SCHLUB a stupid or unattractive person [n -S] : SHLUB
SCHMOE {schmo=n} [n -S]
STUPID mentally slow [adj -PIDER, -PIDEST] : STUPIDLY [adv] / a stupid person [n -S] : STUPIDITY, STUPIDNESS

AIRHEAD a stupid person [n -S]
ASININE obstinately stupid or silly [adj]
ASSHOLE a stupid, incompetent, or detestable person -- an offensive term [n -S]
BEDUNCE to make a dunce of [v -DUNCED, -DUNCING, -DUNCES]
BOOBISH {doltish=adj} [adj]
DODOISM a stupid remark [n -S]
DOLTISH <dolt=n> [adj] : DOLTISHLY, DOLTISHNESS
DULLARD a {dolt=n} [n -S]
DUNCISH <dunce=n> [adj] : DUNCISHLY
FATHEAD a {dolt=n} [n -S]
FATUITY something foolish or stupid [n -ITIES]
FATUOUS smugly stupid [adj]
JUGHEAD a {dolt=n} [n -S]
LUMPISH {stupid=adj} [adj]
LURDANE {lurdan=n} [n -S]
PINHEAD the head of a pin [n -S] : PINHEADED [adj], PINHEADEDNESS
SAPHEAD a foolish, stupid, or gullible person [n -S]
WITLESS lacking intelligence [adj]
UNSMART <smart=adj> [adj]

BONEHEAD a stupid person [n -S]
BUTTHEAD a stupid person [n -S]
CLODDISH <clod=n> [adj] : CLODDISHNESS
CLODPATE a stupid person [n -S] : CLODPATE CLODPOLE CLODPOLL
CLODPOLE {clodpate=n} [n -S] : CLODPATE CLODPOLE CLODPOLL
CLODPOLL {clodpate=n} [n -S] : CLODPATE CLODPOLE CLODPOLL
DUMBHEAD a stupid person [n -S]
DUMBNESS the state of being dumb [n -ES]
DUMFOUND to {astonish=v} [v -ED, -ING, -S]
DUMMKOPF a {dolt=n} [n -S]
GORMLESS {stupid=adj} [adj]
INEXPERT a {novice=n} [n -S] : INEXPERTLY INEXPERTNESS
LUNKHEAD a stupid person [n -S]
MINDLESS lacking intelligence [adj]
MEATHEAD a {dolt=n} [n -S]
NUMSKULL a {dunce=n} [n -S] : NUMBSKULL
STAUMREL a {dolt=n} [n -S]
STOCKISH {stupid=adj} [adj]

STUPIDITY [n -DITIES]
NUMBSKULL {numskull=n} [n -S]
OVERTHICK [adj]
THICKHEAD [n -S] : THICKHEADED
THICKNESS [n -ES]

BUBBLEHEAD [n -S] : BUBBLEHEADED [adj]
CLODHOPPER [n -S] : CLODHOPPING [adj]
DUNDERHEAD [n -S] : DUNDERHEADED [adj]
STUPIDNESS [n -ES]
SUPERTHICK [adj]
WOODENHEAD [n -S] : WOODENHEADED

CHOWDERHEAD [n -S]
CHUCKLEHEAD [n -S] : CHUCKLEHEADED [adj]
DOLTISHNESS [n -ES]
INCOMPETENT [n -S]
NINNYHAMMER [n -S]

CLODDISHNESS [n -ES]
INCOMPETENCE [n -S]
INCOMPETENCY [n -CIES]
INEXPERTNESS [n -ES]

PINHEADEDNESS [n -ES]
UNINTELLIGENT : UNINTELLIGENTLY

* List compiled from OWL2 + Long List by Rebecca Slivka