as
Definitions
Used to indicate that something happens during the time when something else is taking place.
Used to refer to the function, role, or capacity of a person or thing.
Used to introduce a comparison or to indicate that something is the same as something else.
Examples
She works as a software engineer at a large tech company.
As I was walking down the street, it started to rain.
He is not as tall as his older brother.
Synonyms
like while because since in the capacity of whereas seeing that