SAT Book 1 lesson 20 PSAT Vocabulary

happening at the exact same time

ability to discern or discriminate; shrewdness

a rule of action; a principle to live by

a problem or predicament with no obvious resolution

having a bad, offensive odor

impossible to retract or revoke

one who excels in a difficult field at an early age

a strong, stimulating taste

a face or facial expression

a sharp taste; acrid 

to legally certify

to break a promise or obligation; revoke

the use of single atoms & molecules to make microscopic devices

of little importance; insignificant

incorrect; mistaken