Definition
Hapax (Greek: ἅπαξ) means “once” or “once for all.” In soteriology it refers to the singularity and unrepeatable character of Christ’s atoning sacrifice. The word appears technically in Heb. 9:26 (“but now once at the consummation of the ages He has been manifested to put away sin”) and Heb. 10:10 (“we have been sanctified through the offering of the body of Jesus Christ once for all”).
Usage in the Corpus
E.W. Bullinger
Bullinger connects ἅπαξ to the number 14 as the number of deliverance (2 × 7): Christ’s once-for-all offering carries the character of completed, non-repeatable redemption. In his corpus-analysis of Hebrews, he interprets ἅπαξ as the counterpart to the repeated Levitical priesthood — where the Levitical high priest entered the holy of holies year after year, Christ entered once and for all. Bullinger connects this to his monergistic soteriology: salvation is wholly God’s act, once performed and definitively complete. [Bullinger, Number in Scripture]
Origin
In Greek rhetoric and philosophy, ἅπαξ expresses a singular, non-repeated action. As the technical expression hapax legomenon (ἅπαξ λεγόμενον) it denotes a word that occurs only once in a corpus. In the soteriological tradition (the Letter to the Hebrews), the juridical-cultic connotation is primary: the offering is indivisible and complete.