Yes, upper is a Scrabble word!

Adjective

1. The topmost one of two

2. Higher in place or position

3. Superior in rank or accomplishment

Noun

1. The higher of two berths

2. Piece of leather or synthetic material that forms the part of a shoe or boot above the sole that encases the foot

3. A central nervous system stimulant that increases energy and decreases appetite; used to treat narcolepsy and some forms of depression