pleonasm [Grk pleonasmós ‘superabundance, excess’]

The addition of a superfluous expression which is already included in that which is said, e.g. three a.m. in the morning ( solecism). As any figure of speech, pleonasm can serve to strengthen a statement, e.g. I saw it myself, with my own eyes. A related form of semantic redundancy is tautology, the repetition of the same word or sentence. Expressions like boys will be boys only appear to be pleonastic. ( also emphasis)

References

figure of speech

In glossematics, the study of the content plane of language ( expression plane vs content plane).