Periphrasis is a trope whereby a word or a word group directly naming a thing, person or phenomenon (the tenor) is replaced by a circumlocutory descriptive phrase (the vehicle) that mentions some characteristic features of this thing (person, phenomenon). The origin of periphrasis can be traced in kenning, a conventional poetic phrase used for the usual name of a person or thing in Anglo-Saxon poetry, as "wave traveller" for "boat", "ring-giver" for "king", "cavern-warder" for "monster", etc.
Periphrasis is a subtle and effective way of creating imagery: depending on the features it foregrounds it can be pathetic, accusatory, humorous, lofty, etc.
Very often periphrasis has euphemistic implications,i. e. is a mild or vague substitution for a harsh or blunt expression. Antonomasia is a trope whereby the proper name of a person who was distinguished by a particular characteristic is put for a person or a group of persons having the same characteristic. Antonomasia has the merit of brevity and picturesqueness. It describes a person's features and qualities through those commonly associated with the name of some historic figure or of some mythological, religious or literary character.
There is another kind of antonomasia, also involving proper names, in which some characteristic of a person, important from the author's viewpoint, is put for the name of that person.This type of antonomasia is often used in humorous writings.
In the 18th and 19th centuries it was customary to provide literary characters with what is known as "speaking names" which, again, can be treated as another variety of antonomasia Such names not only named a person, but also labelled him with a certain (usually negative) characteristic.