Definition: ad·den·dum *

Pronunciation: \ə-ˈden-dəm\

Function: noun

Inflected Form(s): plural ad·den·da \-ˈden-də\ also: ad·den·dums

Etymology: Latin, neuter of addendus,

gerundive of addere

Date: 1684

1: a thing added  / * a useful addition  ( ADDENDUM|PR ! )
2: a supplement to a book  -

often used in plural but singular in construction