Adjectives that Form the Comparative and Superlative in Two Ways

Adjective	Comparative	Superlative
cruel	crueler/more cruel	cruelest/most cruel
deadly	deadlier/more dearly	deadliest/most deadly
friendly	friendlier/more friendly	friendliest/most friendly
handsome	handsomer/more handsome	handsomest/most handsome
happy	happier/more happy	happiest/most handsome
likely	likelier/more likely	likeliest/most likely
lively	livelier/more lively	liveliest/most lively
lonely	lonelier/more lonely	loneliest/most lonely
lovely	lovelier/more lovely	loveliest/most lovely
narrow	narrower/more narrow	narrowest/most narrow
pleasant	pleasanter/more pleasant	pleasantest/most pleasant
polite	politer/more polite	politest/most polite
quiet	quieter/more quiet	quietest/most quiet
shallow	shallower/more shallow	shallowest/most shallow
sincere	sincerer/more sincere	sincerest/most sincere
stupid	stupider/more stupid	stupidest/most stupid
true	truer/more true	truest/most true