Sentence:  For the occasion on which everyone already <WSD>knows</WSD> everyone else and the host wishes them to meet one or a few honored newcomers , then the `` open house '' system is advantageous because the honored guests are fixed connective points and the drifting guests make and break connections at the door . 
Meaning of the word marked with <WSD> tags:  be familiar or acquainted with a person or an object