preignition

[ pree-ig-nish-uh n ]
/ ˌpri ɪgˈnɪʃ ən /

noun

ignition of the charge in an internal-combustion engine earlier in the cycle than is compatible with proper operation.

Origin of preignition

First recorded in 1895–1900; pre- + ignition

British Dictionary definitions for pre-ignition

pre-ignition
/ (ˌpriːɪɡˈnɪʃən) /

noun

ignition of all or part of the explosive charge in an internal-combustion engine before the exact instant necessary for correct operation