abstruse vs obtuse

accept vs except vs expect

accidental vs incidental

adapt vs adopt

adverse vs averse

advice vs advise

ad vs add

affect vs effect

afterward vs afterword

aisle vs isle

all ready vs already

all together vs altogether

allude vs elude

allusion vs illusion

ambiguous vs ambivalent

among vs between

amoral vs immoral

ascent vs assent

assumption vs presumption

assure vs ensure vs insure

brake vs break

canvas vs canvass

capital vs capitol

cereal vs serial

choose vs chose

coarse vs course

collaborate vs corroborate

complementary vs complimentary

complement vs compliment

comprehensible vs comprehensive

confidant vs confident

conscience vs conscious

consequently vs subsequently

continual vs continuous

council vs counsel

criterion vs criteria