Meaning of X in English

X

(also x ) / eks; NAmE / noun , symbol

■ noun ( pl. Xs , X's , x's / ˈeksɪz; NAmE /)

1.

[ C , U ] the 24th letter of the English alphabet :

'Xylophone' begins with (an) X / 'X'.

2.

[ U ] ( mathematics ) used to represent a number whose value is not mentioned :

The equation is impossible for any value of x greater than 2.

3.

[ U ] a person, a number, an influence, etc. that is not known or not named :

Let's suppose X knows what Y is doing.

—see also X chromosome , X-rated , X-ray

■ symbol

1.

the number 10 in Roman numerals

2.

used to represent a kiss at the end of a letter, etc. :

Love from Kathy XXX.

3.

used to show a vote for sb in an election :

Write X beside the candidate of your choice.

4.

used to show that a written answer is wrong

—compare tick noun (1)

5.

used to show position, for example on a map :

X marks the spot.

Oxford Advanced Learner's English Dictionary.      Оксфордский английский словарь для изучающик язык на продвинутом уровне.