"Unique"

We rightly wince when someone refers to some object, event or person as 'more unique' than another, but often overlook less patently absurd uses of the word.

Applied to any particular individual object or event 'X is unique' is vacuously tautological. Provided we take into account all properties, including temporal and spatial, there cannot be two individuals with precisely the same properties, since to assert there are two individuals meetings a certain description implies there is some way of distinguishing them, because we need to distinguish them in order to count them.

If "unique" is to be used to assert anything untrivial it must apply not to an individual but to a particular description of an individual. For instance compare:
(1) Boris Johnson is unique in being a British Prime Minister living with his mistress in Downing Street
(2) Boris Johnson is unique in being Boris Johnson

(1) and (2) are both true, but only (1) is informative.