Heads up! Here’s a few, under the letter “u,” you better take heed when you use.
undo Unfasten; nullify
undue Exceeding or violating propriety or fitness
[unequivocably] No such word!
unequivocally Leaving no doubt; unambiguous
understated Stated in restrained terms
unwanted Not wanted
unwonted Rare; unusual
urban Of, relating to, or constituting a city
urbane Suave; sophisticated
See my master list of all the homonyms, homophones, and other confusingly similar words I’ve posted to date