<p><strong>Noun</strong></p><ul><li>A thing to be added; an addition.</li><li>An appendix to a book.</li><li>The radial distance between the tip of a gear tooth and the pitch circle of a gear or the pitch line of a rack.</li><li>Also called addendum circle: an imaginary circle touching the tips of the teeth on a gear.</li></ul><p><strong>End of Response</strong></p>