What is the X in X-mas?
c.1400, folk etymology of Old English wermod "wormwood," related to vermouth, but the ultimate etymology is unknown. Cf. Old Saxon wermoda, Dutch wermoet, Old High German werimuota, German Wermut. Weekley suggests wer "man" + mod "courage," from its early use as an aphrodisiac. Figurative use, however, is usually in reference to its bitter aftertaste. Perhaps because of the folk etymology, it formerly was used to protect clothes and bedding from moths and fleas. "A medecyne for an hawke that hath mites. Take the Iuce of wormewode and put it ther thay be and thei shall dye." ["Book of St. Albans," 1486]
Heb. la'anah, the Artemisia absinthium of botanists. It is noted for its intense bitterness (Deut. 29:18; Prov. 5:4; Jer. 9:15; Amos 5:7). It is a type of bitterness, affliction, remorse, punitive suffering. In Amos 6:12 this Hebrew word is rendered "hemlock" (R.V., "wormwood"). In the symbolical language of the Apocalypse (Rev. 8:10, 11) a star is represented as falling on the waters of the earth, causing the third part of the water to turn wormwood. The name by which the Greeks designated it, absinthion, means "undrinkable." The absinthe of France is distilled from a species of this plant. The "southernwood" or "old man," cultivated in cottage gardens on account of its fragrance, is another species of it.
any bitter or aromatic herb or shrub of the genus Artemisia of the family Asteraceae, distributed throughout many parts of the world. These plants have many small, greenish yellow flower heads grouped in clusters. The leaves are usually divided and alternate along the stem; they may be green, grayish green, or silvery white.