denotes "a mass of rock," as distinct from petros, "a detached stone or boulder," or a stone that might be thrown or easily moved. For the nature of petra, see Matthew 7:24,25; 27:51,60; Mark 15:46; Luke 6:48 (twice), a type of a sure foundation (here the true reading is as in the RV, "because it had been well builded"); Revelation 6:15,16 (cp. Isaiah 2:19 ,ff.; Hosea 10:8 ); Luke 8:6,13 , used illustratively; 1 Corinthians 10:4 (twice), figuratively, of Christ; in Romans 9:33; 1 Peter 2:8 , metaphorically, of Christ; in Matthew 16:18 , metaphorically, of Christ and the testimony concerning Him; here the distinction between petra, concerning the Lord Himself, and Petros, the Apostle, is clear (see above).
"a rock or reef," over which the sea dashes, is used in Jude 1:12 , "hidden rocks," RV, metaphorical of men whose conduct is a danger to others. A late meaning ascribed to it is that of "spots," (AV), but that rendering seems to have been influenced by the parallel passage in 2 Peter 2:13 , where spiloi, "spots," occurs.