Part-of-Speech: Preposition, +AD
Inflection: Indeclinable = Indeclinable word (preposition, conjunction, ...)
Streitberg 1910, p. 1535
uf (ub-uh, 111.232) Präp. unter I. [m. Akk. (Richtung)] II. [m. Dat. (Ruhe)]