Hebrews la'anah, the Artemisia absinthium of botanists. It is noted for its intense bitterness (Deuteronomy 29:18; Proverbs 5:4; Jeremiah 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 (Revelation 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.

Noah Webster's New International Dictionary of the English Language

1. (n.) A composite plant (Artemisia Absinthium), having a bitter and slightly aromatic taste, formerly used as a tonic and a vermifuge, and to protect woolen garments from moths. It gives the peculiar flavor to the cordial called absinthe. The volatile oil is a narcotic poison. The term is often extended to other species of the same genus.

2. (n.) Anything very bitter or grievous; bitterness.