To make an item unique or to create a unique index for a list of items, especially in the context of SQL databases. (Alternate spelling: uniquefy)

when you've done something so cringe you can't stop replaying it in your head and it stops you from getting on with your every day life

To remove non-unique items from a collection of items.

to make unique, to alter existing
ambiguous conditions until an object can be singularly identified among like objects