To happen or take place.
The liftoff will occur in exactly twelve seconds.
To present or offer itself.
I will write if the opportunity occurs.
To come or be presented to the mind; to suggest itself.
To be present or found.
The chemical monofluoroacetate occurs in all parts of Dichapetalum cymosum, and is responsible for its toxic effects.
An instance of something occurring; an event or happening.
(in combination) That occurs in a specified manner.
naturally occurring macromolecules