To enlist oneself (in something) or become a member (of something)
To enter (a name, etc.) in a register, roll or list
To enlist (someone) or make (someone) a member of
To commit oneself, as to a project, a goal, an organization, a cause.
To begin broadcasting a radio or television signal, usually at the beginning of a broadcasting day and after being off the air for several hours.
To join something, after signing.
To apply to receive unemployment benefits.
To log on; to start using a computer, radio, etc., or to start talking.
The time of day when a radio or television station begins broadcasting, usually after being off the air for several hours.