1. Occurring or likely to occur as an unpredictable or minor consequence: "the principle that even annoying, intrusive, and offensive speech is to be protected by the courts and tolerated by the public as incidental to an open society" (Frederick Schauer). See Synonyms at accidental.
2. Of a minor, casual, or subordinate nature: incidental expenses.
A minor accompanying item or expense: a pocket in the suitcase for incidentals.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.