Oder (a major river in the Czech Republic, Poland and Germany)

or

(tag question) right?; is it?; is it not?

and/or

(electronics) OR gate, a logic gate performing a Boolean logic OR operation

dative plural of ODER-Gatter

genitive singular of ODER-Gatter

trick or treat!

...or not, disregard, aside; expressing the will to ignore the nature/status of something or someone

Ellipsis of Vogel, friss oder stirb.; take it or leave it