- [countable, uncountable]
the 24th letter of the English alphabet 英語字母表的第 24 個字母 ‘Xylophone’ begins with (an) X/‘X’. xylophone 一詞以字母 x 開頭。
- [uncountable] (
mathematics )數學 used to represent a number whose value is not mentioned (代表未知數) - [uncountable]
a person, a number, an influence, etc. that is not known or not named 未知的人(或數、影響等);未指明的人(或數、影響等) see also X chromosome, X-rated, X-ray