Ẹyọ tíkòsí: Ìyàtọ̀ láàrin àwọn àtúnyẹ̀wò

[[File:ImaginaryUnit5.svg|thumb|right|'''''i''''' in the [[complex plane|complex]] or [[Cartesian plane|cartesian]] plane; real numbers fall on the horizontal axis, and imaginary numbers fall on the vertical axis]]

Ninu [[mathematics|mathimatiki]], '''ẹyọ tíkòsí''' (''imaginary unit'') n fun sistemu [[real number|nomba gidi]] <math>\mathbb{R}</math> laye lati fe de sistemu [[complex number|nomba sisoro]] <math>\mathbb{C}</math>&nbsp;. O se ko sile pelu ''i'' tabi ''j'' tabi leta Greek [[iota]].