imaginary unit

noun

UK /ɪˈmædʒ.ɪ.nər.i ˈjuː.nɪt/

US /ɪˈmædʒ.ə.ner.i ˈjuː.nɪt/

A special number called i that stands for the square root of minus one.

In math class, we learned that the imaginary unit i squared equals negative one.

SYNONYMS

i unit imaginary number square root of negative one imaginary number i

RELATED WORDS

complex number real number square root negative one imaginary number

OTHER MEANINGS

2. The basic building block used to make imaginary and complex numbers.

Every imaginary number can be written as a real number times the imaginary unit.

3. A number that is not on the normal number line but helps solve equations like x squared plus one equals zero.

Using the imaginary unit, we can solve x² + 1 = 0 and get x = i.

4. The symbol i used in algebra to represent the square root of -1.

When you multiply i by itself, you get -1 because i is the imaginary unit.