What is the meaning of off?

Answer 1

As an adverb, as in 'the woman ran off'

As a preposition, as in 'he rolled off the sofa bed'

As an adjective, as in ' having an off day'

As a noun, as in ' the race is ready for the off'

As a verb used informally, as in 'the crowd was up and off'

Answer 2

Get off the bus: opposite is to get on the bus.
Switch off the light: opposite is to switch on the light.
Put off going shopping until tomorrow as the weather is atrocious.