Noun

1. An intensely bitter herb (Artemisia absinthium) used in the production of absinthe and vermouth, and as a tonic.
   • William Shakespeare, Romeo and Juliet, Act I, Scene iii (the nurse's monologue).

     But as I said, / When it did taste the wormwood on the nipple / Of my dug and felt it bitter, pretty fool, / To see it tetchy and fall out with the dug! /

2. Anything that causes bitterness or affliction.