Adam Clarke on Acts 10:14

Common or unclean - By common, κοινον, whatever was in general use among the Gentiles is to be understood; by ακαθαρτον, unclean, every thing that was forbidden by the Mosaic law. However, the one word may be considered as explanatory of the other. The rabbins themselves, and many of the primitive fathers, believed that by the unclean animals forbidden by the law the Gentiles were meant.