What is the X in X-mas?
c.1300, fysike, "art of healing, medical science," also "natural science" (c.1300), from Old French fisike "natural science, art of healing" (12c.) and directly from Latin physica (fem. singular of physicus) "study of nature," from Greek physike (episteme) "(knowledge) of nature," from fem. of physikos "pertaining to nature," from physis "nature," from phyein "to bring forth, produce, make to grow" (cf. phyton "growth, plant," phyle "tribe, race," phyma "a growth, tumor") from PIE root *bheue- "to be exist, grow" (see be). Spelling with ph- attested from late 14c. (see ph). As a noun, "medicine that acts as a laxative," 1610s. The verb meaning "to dose with medicine" is attested from late 14c.
physic phys·ic (fĭz'ĭk)
A medicine or drug, especially a cathartic.