(anatomy, zootomy) A narrow-edged tooth at the front of the mouth of mammals, between the canines and adapted for cutting; in humans there are four in each jaw.

Pertaining to or engaging in incest. / Characterized by mutual relationships that are intimate and exclusive to the detriment of outsiders.

The creation or beginning of something; the establishment. / A layering, nesting, or recursion of something.

A cut, especially one made by a scalpel or similar medical tool in the context of surgical operation; the scar resulting from such a cut. / The act of cutting into a substance.

Loosely associated; of limited relevance except indirectly; only accidentally related. / Existing tangentially, being a byproduct, a tangent, or a likely consequence. / Occurring by chance.

Minor items, not further defined. Incidental expense. / Something that is incidental.

Capable of, or used for, or actually causing fire. / (figuratively) Intentionally stirring up strife, riot, rebellion. / (figuratively) Inflammatory, emotionally charged.

Something capable of causing fire, particularly a weapon. / One who maliciously sets fires. / (figuratively) One who excites or inflames factions into quarrels.

(manner) In an incidental manner; not of central or critical importance. / By chance; in an unplanned way. / (speech act, conjunctive) Parenthetically, by the way.

(graph theory) A matrix showing the relationship between two classes of objects.