Definition:Singular Statement/Individuating Description

Definition
An individuating description is a predicate whose purpose is to uniquely identify a particular object.

Example
The King of Siam in 1860 is an individuating description.

It uniquely identifies the (one) person who was ruler of the nation of Siam during the year 1860.

Also see

 * Proper Name

Note that while a proper name also does the job of uniquely identifying a particular object, the specific object identified by an individuating description may change in the course of time.