Enybrizo (ἐνυβρίζω) combines en (in/against) with hybrizo (to treat with insolence, insult). It appears only once in the New Testament — in Hebrews 10:29 — in one of the most solemn warning passages in all of Scripture. The writer asks: how much more severely should one be punished who has 'insulted/outraged [enybrizo] the Spirit of grace?' This single use carries enormous weight: it defines what apostasy ultimately is — a deliberate insult against the very Spirit who extends God's grace.
Hebrews 10:29 sets out a triple offense of apostasy: trampling the Son of God underfoot, treating as unholy the blood of the covenant, and enybrizo-ing the Spirit of grace. The escalating severity is striking — the worst of the three is the outrage against the Holy Spirit. This connects to Jesus's warning about the 'unforgivable sin' (blasphemy against the Holy Spirit, Matthew 12:31-32). To deliberately reject the gracious work of the Spirit after receiving the knowledge of truth is to slam the door on the very source of forgiveness and transformation.