[dih-den-duh m]
noun, plural de·den·da [dih-den-duh] /dɪˈdɛn də/. Machinery.
  1. (on a gear or rack) the radial distance between the pitch circle or line and the root circle or line.Compare addendum(def 3a).

Origin of dedendum

1900–05; < Latin: to be given up, gerund of dēdere, equivalent to dē- de- + -dere combining form of dare to give; see addendum Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018