1 upper /ˈʌpɚ/ adjective
1 upper
Learner's definition of UPPER
always used before a noun
: located above another or others of the same kind
: located at or near the top
: located toward the north
: above another or others in position, rank, or order

stiff upper lip

see 1stiff
2 upper /ˈʌpɚ/ noun
plural uppers
2 upper
plural uppers
Learner's definition of UPPER
: the parts of a shoe or boot above the sole
informal : a drug that gives you more energy

on your uppers

British, old-fashioned + informal
: having very little money