sign in

verb

1. To sign one's name on a list when entering a place, to indicate one's arrival.

   “In order to get into the office after hours, you'll have to sign in at the security desk.”

   “Harper signed in with the rangemaster and handed him her gun. He reloaded it with six shells and handed it back, together with two sets of ear defenders.”

2. To take some action to access a secured program or web page on a computer; to log in.

   “He signed in using his own cybername: Point Guard.”