Definition of: incidental

(in′sə·den′təl) adjective
1. Occurring in the course of something else; contingent.
2. Happening without regularity or design; casual.
—noun
1. Something that is incidental, contingent, or fortuitous; a subordinate or minor occurrence, circumstance, or result.
2. Music In the tonic sol–fa system, a tone foreign to a chord.
3. Usually plural Minor or casual expenses or items.
—in′ci·den′tal·ly adverb Synonyms (adj.): accessory, accidental, casual, chance, collateral, concomitant, concurrent, contingent, fortuitous, occasional. That is incidental which comes in the regular course of things, but is not viewed as primary or important; as, an incidental allusion, reference, or mention. That which is incidental is subordinate to the main design; that which is accidental occurs without design. Compare ACCIDENT. Antonyms: essential, fundamental, independent, inherent, invariable, regular, systematic, underlying.