IPA: /nɒnˈruːtiːn/
KK: /nɑnˈrutɪn/
Something that is not part of a regular or usual pattern or process.
The project required nonroutine tasks that challenged the team.
Nonroutine → It is formed from "non-" (meaning not) and "routine" (from Old French *routine*, meaning a regular course of procedure). The word "nonroutine" means not following a regular course or procedure, indicating something that is unusual or out of the ordinary.
Think of 'non-' meaning 'not' and 'routine' referring to a regular procedure — so nonroutine describes something that is not regular or usual.