dedendum
noun
de·den·dum
də̇ˈdendəm,
dēˈ-
plural -s
: the root of a gear tooth
also : the distance between the dedendum circle and pitch circle of a gear wheel or rack compare addendum
Word History
Etymology
Latin, neuter of dedendus, gerundive of dedere to give up, deliver, from de from, away + -dere (from dare to give); from the contrast with the addendum of a gear tooth