sideline
noun [ C ]
uk/ˈsaɪdlaɪn/ usa business activity that someone does in addition to their main business:
For many companies, producing own-label goods is not a sideline, it's a strategy for growth.
a sideline in sth The company has been developing a sideline in closed-circuit television since buying the electronics business last year.
on the sidelines
not being used or not involved in an activity:
The absence of new products is keeping consumers on the sidelines.
stay/wait/sit on the sidelines
sideline
verb [ T ]
uk/ˈsaɪdlaɪn/ usto force someone or something into a situation in which they have less influence or importance than before:
After I got pregnant, I felt that my bosses were sidelining me.
The oil industry would be very unhappy if this legislation was sidelined.