Existing only in your mind or imagination; not real or actually present.
From Latin 'imaginarius' (existing in imagination), derived from 'imago' (image). The word passed through Old French into Middle English, maintaining its sense of something that exists as a mental image rather than physical reality.
In mathematics, imaginary numbers are as 'real' as regular numbers when solving equations—showing that 'imaginary' doesn't mean worthless, just existing in a different dimension than physical reality.
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