'Custom' in the Bible

And certain men came down from Judaea and taught the brethren,'saying , Except ye be circumcised after the custom of Moses, ye cannot be saved.

and Paul, as his custom was, went in unto them, and for three sabbath days reasoned with them from the Scriptures,

To whom I answered, that it is not the custom of the Romans to give up any man, before that the accused have the accusers face to face, and have had opportunity to make his defense concerning the matter laid against him.