Extended Strong's Greek Lexicon (Abbott-Smith based)
firstborn
Usage: πρωτότοκος, -ον (πρῶτος, τίκτω) [in LXX chiefly for בְּכוֹר ;] first-born: Luk.2:7; pl., Heb.11:28. Metaphorical, of the priority of Christ (originally perh. a Messianic title, cf. Psa.89:28, Heb.1:6; see ICC on Col.1:15): Heb.1:6; π. πάσης κτίσεως, Col.1:15; ἐν πολλοῖς ἀδελφοῖς, Rom.8:29; π. (ἐκ) τ. νεκρῶν, Col.1:18, Rev.1:5; pl., of the elect, ἐκκλησία πρωτοτόκων, Heb.12:23.† (AS)