sign on

Short definition from Wiktionary

Verb

1. 1
   To join something, after signing.
2. 2
   To commit oneself, as to a project, a goal, an organization, a cause.
3. 3
   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.
4. 4
   To log on; to start using a computer, radio, or other multicast device; to start talking.
5. 5
   To apply to receive unemployment benefits.

Noun

1. 1
   Nonstandard spelling of sign-on.
2. 2
   The username and password for logging in to a computer account.
3. 3
   An attempt to log in.
4. 4
   An instance of signing on to something.
5. 5
   A person who signs on to something.
6. 6
   A verbal script that is repeated at the start of every instance of something, as a form of greeting and identification.
7. 7
   A signing bonus.