ADDENDUM

addendum, supplement, postscript

(noun) textual matter that is added onto a publication; usually at the end

Source: WordNet® 3.1

Etymology

Noun

addendum (plural addenda or addendums)

Something to be added; especially text added as an appendix or supplement to a document.

A postscript.

(engineering) The height by which the tooth of a gear projects beyond (outside for external, or inside for internal) the standard pitch circle or pitch line.

Source: Wiktionary

Ad*den"dum, n.; pl. Addenda. Etym: [L., fr. addere to add.]

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

Source: Webster’s Unabridged Dictionary 1913 Edition