What it means

1. adjective higher in place or position
   “the upper bunk”
2. adjective superior in rank or accomplishment
   “the upper half of the class”
3. adjective the topmost one of two
4. noun piece of leather or synthetic material that forms the part of a shoe or boot above the sole that encases the foot
   “Uppers come in many styles”
5. noun the higher of two berths
6. noun a central nervous system stimulant that increases energy and decreases appetite