tähisena
X = 10 rooma numbrina (10 in Roman numerals)
X = muu sugu, kui M = mees ja N = naine

(a non-binary gender, where F = female, M = male)
X = X Window System
X = _ITU-T X Series Recommendations:
"Data networks, open system communications and security"_
X = tundmatu (unknown)
X (media rating) = ainult täiskasvanuile
(for adults only)
x = algebraline muutuja (algebraic variable)
x = rõhttelg ristkoordinaatides
(horizontal axis in Cartesian coordinates)