Higher in place, position, or rank: the upper bunk; the upper half of the class. Situated on higher ground: upper regions. Lying farther inland: the upper Nile. Northern: the upper Midwest. Geology & Archaeology Of, relating to, or being a later division of the period named. Denoting the smaller and usually less broadly representative house of a bicameral legislature. The part of a shoe or boot above the sole. Informal An upper berth. Informal The upper teeth or a set of upper dentures. Slang A drug, especially an amphetamine, used as a stimulant. Slang An exhilarating or euphoric experience. on (one's) uppers Informal Impoverished; destitute.