An Etymological Dictionary of Astronomy and Astrophysics

The measure of “peakedness” of the curve describing a frequency distribution in the region about its mode. The kurtosis of the normal distribution is 0.

Etymology (EN): From Gk. kurtosis “bulging, curvature,” from kurtos “convex,” kirkos “a ring;” cf. Av. skarəna- “round;”
L. circus “circle, ring;” PIE base *sker- “to turn, bend.”

Etymology (PE): Afrâštegi condition, state adj. of afrâšté “elevated, erect, upright,” p.p. of afrâštan “to raise, exalt, extole,” from Mid.Pers. abrâstan, abrâz- “to lift, raise,”
from ab-, from O.Pers./Av. abiy-/aiwi- “to, upon, against;” cf. Skt. abhi-, Gk. amphi- + râst “straight, direct, true;”
from O.Pers. rāsta- “straight, true,” rās-
“to be right, straight, true;” Av. rāz- “to direct, put in line, set,” razan- “order;” cf. Skt. raj- “to direct, stretch,” rjuyant- “walking straight;” Gk. orektos “stretched out;” L. regere “to lead straight, guide, rule,” p.p. rectus “right, straight;” Ger. recht; E. right; PIE base *reg- “move in a straight line,” hence, “to direct, rule.”