preposition
except, apart from
A2
Außer: a preposition meaning 'except' or 'apart from' (e.g., außer mir). It typically governs the dative case. In some fixed expressions it may appear with genitive or no case, but dative is standard. Commonly used to exclude people or things from a group or statement.
Examples
Außer dem Chef waren alle da.
Except for the boss, everyone was there.
Außer dir habe ich niemanden eingeladen.
Apart from you, I didn't invite anyone.
Außer dem Direktor wusste niemand von der Entscheidung, weil die Nachricht spät versendet wurde.
Except for the director, nobody knew about the decision because the message was sent late.
Details
Mnemonics
imagine a group with one person standing outside a circle labeled 'außer' (outside)
sounds like 'ow-ser' -> 'except'
Notes
außer normally governs the dative (außer mir, außer dem Mann). It can mean 'except' or 'besides/apart from' depending on context.