τετράς

Etymology
From (whence also ) +.

Noun

 * 1) the number four
 * 2) the fourth day of the month
 * 3) the fourth day of the week
 * 4) a period of four days
 * 5) the four quarters of the moon
 * 6) tetrarchy
 * 7) four-leaved pamphlet, quaternion