You will receive two points for each word that is used correctly in a sentence and two points for each correctly described connotation.
thrifty, frugal
slender, skinny
mix-breed, mutt
aggressive, militant
teacher, professor
piano player, pianist
obese, overweight
shy, wary
clever, conniving
feign, pretend

Sentences for the words...
thrifty - He was thrifty and anxious to leave to his son a full treasury.

 frugal -
In business transactions Alex was frugal with his money, but when it came to his family.

slender - 
They were both so tall and slender - their movements smooth and measured.

skinny -
All her dresses now fit snugly across the bust, and even her skinny legs were beginning to have some attractive curves.