What is the X in X-mas?
early 15c., "relieve (pain)," from Latin mitigatus, past participle of mitigare "soften, make tender, ripen, mellow, tame," figuratively, "make mild or gentle, pacify, soothe," ultimately from mitis "gentle, soft" (from PIE *mei- "mild") + root of agere "do, make, act" (see act). First element is from PIE root *mei- "soft, mild." Related: Mitigated; mitigating; mitigates.
mitigate mit·i·gate (mĭt'ĭ-gāt')
v. mit·i·gat·ed, mit·i·gat·ing, mit·i·gates
To moderate in force or intensity.