The Collaborative International Dictionary of English v.0.48:
log in \log in\, log on \log on\, v. i. (Computers) To establish communication with a host computer from a terminal or remote computer. [PJC] LogisticWordNet (r) 3.0 (2006):
log on v 1: enter a computer; "Have you logged in lately?" [syn: log in, log on, log-in] [ant: log off, log out]