Cephas
Archimandrite Nikifor’s Biblical Encyclopedia
(stone) (John 1:42; Gal 2:9) - the Syriac-Chaldean equivalent of the Greek Peter, meaning rock or stone. The Lord gave Simon son of Jonah this name, foreseeing the firmness of his faith and character, when he solemnly confessed, 'Thou art the Christ, the Son of the living God' (Matt 16:16-18). Paul often calls Peter Cephas (1 Cor 1:12; 3:22; 9:5 and elsewhere), while Peter uses his Greek name in his own epistles (1 Pet 1:1; 2 Pet 1:1).