Webster's Revised Unabridged Dictionary · 1913

Addendum

Addendum ({not transcribed}) , noun

[Latin, from addere to add.]

A thing to be added; an appendix or addition.
Collocations (1)
Addendum circle (Mechanics) , the circle which may be described around a circular spur wheel or gear wheel, touching the crests or tips of the teeth. — Rankine