Periphrasis - is a round - about way of speaking used to name some object or phenomenon. Longer-phrase is used instead of a shorter one. Some periphrasis are traditional.
e. g. The fair sex.
My better half.
Periphrasis are divided into:
1. Logical - based on inherent properties of a thing.
e. g. Instrument of destruction, the object of administration.
2. Figurative - based on imagery: metaphor, metonymy
e. g. To tie a knot - to get married; in disgrace of fortune - bad luck.