1. complex number, complex quantity, imaginary, imaginary number

(mathematics) a number of the form a+bi where a and b are real numbers and i is the square root of -1

Synonyms

• complex number
• complex quantity
• imaginary number

2. fanciful, imaginary, notional

not based on fact; unreal

Example Sentences:
'the falsehood about some fanciful secret treaties'
'a small child's imaginary friends'
'to create a notional world for oneself'

Synonyms

• fanciful
• notional