The Greek eisporeuomai is a common verb meaning to enter or go into. Jesus uses it in Mark 1:21 ('They went to Capernaum') and more significantly in the debate over clean and unclean: 'Nothing outside a person can defile them by going into (eisporeuomenon) them. Rather, it is what comes out of a person that defiles them' (Mark 7:15). It appears in Acts 28:30 of visitors coming to Paul during his house arrest.
Jesus' use of eisporeuomai in Mark 7:15-18 is theologically revolutionary. What enters (eisporeuomenon) does not defile — this overturns the entire system of dietary law at the level of principle, though not yet in explicit declaration (Mark 7:19 adds the editorial note 'declaring all foods clean'). The true locus of defilement is the human heart: 'from within, out of the heart of man, come evil thoughts' (Mark 7:21). The eisporeuomai debate became the theological basis for the Gentile mission — if entering does not defile, neither does table fellowship with Gentiles.