Pluralis Majestatis, literally Grandiose Plural, is the use of the plural pronoun in reference to one individual her-, him-, or itself alone. This is also known as the Royal we.

Examples of purported instances:

We are not amused. Queen Victoria

To be distinguished from Pluralis modestiae, also Pluralis Auctoris (inclusion of readers or listeners). For instance:

Let's calculate! Leibniz
We are thus led also to a definition of 'time' in physics. Albert Einstein