incidental

UK: /ˌɪnsɪˈdɛnt^əl/ US: /ˌɪnsɪˈdɛntəl/ ,(in′si den′tl)

WordReference Random House Learner's Dictionary of American English © 2025

in•ci•den•tal /ˌɪnsɪˈdɛntəl/   adj. 

1. likely to happen in an unplanned manner:
   Incidental expenses were paid for by his employer.

n. [countable]

2. something incidental.
3. incidentals, [plural] minor expenses.

See -cide-.

WordReference Random House Unabridged Dictionary of American English © 2025

in•ci•den•tal  (in′si den′tl), adj. 

1. happening or likely to happen in an unplanned or subordinate conjunction with something else.
2. incurred casually and in addition to the regular or main amount:
   incidental expenses.
3. likely to happen or naturally appertaining (usually fol. by to).

n. 

4. something incidental, as a circumstance.
5. incidentals, minor expenses.

• incident + -al¹ 1610–20

in′ci•den′tal•ness, n. 
Synonyms

• 1. casual, chance, fortuitous; contingent.

Antonyms

• 1. fundamental.

Collins Concise English Dictionary © HarperCollins Publishers::

incidental / ˌɪnsɪˈdɛnt^əl/ adjective

1. happening in connection with or resulting from something more important; casual or fortuitous
2. (postpositive) followed by to: found in connection (with); related (to)
3. (postpositive) followed by upon: caused (by)
4. occasional or minor: incidental expenses

noun

1. (often plural) an incidental or minor expense, event, or action

ˌinciˈdentalness noun