Adam Clarke

But fornication - It is probable that the three terms used here by the apostle refer to different species of the same thing. The word fornication, πορνεια, may imply not only fornication but adultery also, as it frequently does; uncleanness, ακαθαρσια may refer to all abominable and unnatural lusts - sodomy, bestiality, etc., and covetousness, πλεονεξια, to excessive indulgence in that which, moderately used, is lawful. As the covetous man never has enough of wealth, so the pleasure-taker and the libertine never have enough of the gratifications of sense, the appetite increasing in proportion to its indulgence. If, however, simple covetousness, i.e. the love of gain, be here intended, it shows from the connection in which it stands, (for it is linked with fornication, adultery, and all uncleanness), how degrading it is to the soul of man, and how abominable it is in the eye of God. In other places it is ranked with idolatry, for the man who has an inordinate love of gain makes money his god. Let it not be once named - Let no such things ever exist among you, for ye are called to be saints.