Imagination; fancy.

(mathematics) An imaginary number.

(sociology) The set of values, institutions, laws, and symbols common to a particular social group and the corresponding society through which people imagine their social whole.

Existing only in the imagination.

(mathematics, of a number) Having no real part; that part of a complex number which is a multiple of − 1 {\displaystyle {\sqrt {-1}}} (called imaginary unit).