What is the X in X-mas?
1680s, in reference to the gland in the brain, from French pinéal, literally "like a pine cone," from Latin pinea "pine cone," from pinus "pine tree" (see pine (n.)).
pineal pin·e·al (pĭn'ē-əl, pī'nē-)adj.
Having the form of a pine cone.
Of or relating to the pineal body.