preposition
around (time), around/about
A1
um is a German preposition meaning 'around' (time) or 'around/about' (approximation). It governs the accusative — use 'um' with exact times (um 8 Uhr) and for movement around something. For time approximations often also 'gegen' or 'gegen etwa' may be used. No gender; always accusative case.
Examples
Der Zug kommt um acht Uhr an.
The train arrives at eight o'clock.
Die Freunde trafen sich um Mitternacht, damit sie gemeinsam den Film sahen.
The friends met at midnight so that they could watch the film together.
Er ging um den See herum.
He walked around the lake.
Details
Mnemonics
a circle around a clock face
sounds like 'oom' — imagine a clock's hands circling (around)