Adjective
expendable - Not essential, able to be used up or sacrificed without significant loss, easily replaced or not necessary for long-term use.

The workers didn't feel any sense of job security, and they felt expendable, because they were fired whenever the demand for the factory work slowed down.
simultaneous - Refers to actions or events that are performed or experienced at the same time, without any time between them.

They made a simultaneous broadcast of the event across multiple time zones that allowed people from all over the world to watch it live.