log in → σύνδεση, συνδέομαι
log on
sign in (third-person singular simple present signs in, present participle signing in, simple past and past participle signed in)
(idiomatic) To sign one's name on a list when entering somewhere.
(computing) To take some action to access a secured program or web page on a computer; to log in.
https://en.wiktionary.org/wiki/sign_in