ĉu

Etymology
From, or the related.

Particle

 * 1) interrogative particle
 * 2) whether, if
 * 3)  whether ... or
 * 4)  whether ... or not
 * 1)  whether ... or
 * 2)  whether ... or not
 * 1)  whether ... or
 * 2)  whether ... or not

Usage notes
Ĉu as a tag question marker is a shortening of the sentence ender, but carries a slightly different connotation and seems to be a relatively new invention, from the 1990s onwards.