addendum: Meaning and Definition of

ad•den•dum

1. a thing to be added; an addition.
2. an appendix to a book.
1. the radial distance between the tip of a gear tooth and the pitch circle of a gear or the pitch line of a rack. Cf. dedendum.
2. Also calledadden&prim;dum cir&prim;cle.an imaginary circle touching the tips of the teeth on a gear.