Some Commonly Confused Words in English Language:
Perspicuous: expressing things clearly, with perspicacious: having ready understanding of things.
Complacent: smug and self-satisfied, with complaisant: willing to please.
Appraise: assess, with apprise: inform.
Discreet: careful not to attract attention or give offence, with discrete: separate, distinct.
Loose: unfasten or set free, with lose: cease to have, become unable to find.
Principal: first in order of importance, with principle: a basis of a system of thought or belief.
Affect: make a difference to, with effect: a result, bring about a result.
Loath: reluctant; unwilling, with loathe: dislike greatly.