ikso

Noun

 * 1) the letter x (upper case: X), twenty-fourth letter of the Latin alphabet

Usage notes
Esperanto does not use the letter x. When roots from other languages are adopted into Esperanto, the letter x gets converted to "ks" or "kz".

However, there is a common convention, where Esperanto's accented letters (ĉ, ĝ, ĥ, ĵ, ŝ, ŭ) cannot be typed, of signifying them with a following x (cx, gx, hx, jx, sx, ux). This is referred to as, , or.