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