Extended Strong's Greek Lexicon (Abbott-Smith based)
reef
Usage: σπιλάς, -άδος, ἡ (on the gender in Ju, l.with, see Mayor, Ju., 41), __1. poët. in cl., a rock or reef over which the sea dashes (Polyb., FlJ, al.). Metaphorical, of men whose conduct causes danger to others, Ju 12, R, txt. (but see infr.). __2. In late writers = σπίλος (which see), a spot, stain; metaphorically, Ju, l.with, R, mg. (cf. Mayor, 41, but see supr.).† (AS)