aesthetic

(adj) responsive to or appreciative of what is pleasurable to the senses
My new boyfriend has an aesthetic eye for fashion which makes him stand out in a crowd.

alacrity

(n) promptness in response; a cheerful readiness
The coffee shop barista responded to customers with such alacrity that some wondered how many cups of coffee he drank in a day.

affable

(adj) characterized by ease and friendliness
The professional baseball player is so affable that he stays long after each game to autograph all of his fans' baseballs.

alleviate

(v) relieve, lessen
The Tylenol helped to alleviate my headache and I'm starting to feel much better.

altruism

(n) unselfish regard for or devotion to the welfare of others
The stranger showed altruism when she dove into the river and saved the baby.

ambiguous

(adj) capable of being understood in two or more possible senses or ways
I'm so confused by the ambiguous answer Kate gave me when I asked her out to the movies that I have no idea if she'll show up or not.
 

amalgam

(n) a mixture of different elements
Sixth Street in Austin, Texas features an amalgam of musical styles but I love each one all the same.

ambivalent

(adj) simultaneous and contradictory attitudes or feelings
Pedro didn't like either candidate so he remained ambivalent about who to vote for until the day of the election.