/ ˌɪnsɪˈdentl; NAmE / adjective , noun
■ adjective
1.
incidental (to sth) happening in connection with sth else, but not as important as it, or not intended :
The discovery was incidental to their main research.
incidental music (= music used with a play or a film / movie to give atmosphere)
You may be able to get help with incidental expenses (= small costs that you get in connection with sth) .
2.
incidental to sth ( technical ) happening as a natural result of sth :
These risks are incidental to the work of a firefighter.
■ noun
[ usually pl. ] something that happens in connection with sth else, but is less important :
You'll need money for incidentals such as tips and taxis.
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WORD ORIGIN
early 17th cent.: originally from medieval Latin incidentalis , from Latin incident- falling upon, happening to, from the verb incidere , from in- upon + cadere to fall.