Definition from Wiktionary, the free dictionary
- Loosely associated; existing as a byproduct, tangent, or accident.
- That character, though colorful, is incidental to the overall plot.
- Entering or approaching, prior to reflection (more frequently incident).
Related terms 
Derived terms 
incidental (plural incidentals)
- Incidental expense.
- She's costing us a lot in incidentals.