occurring

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”