Abarim Publications' online Biblical Hebrew Dictionary
לענה
The word לענה (l'ana) means wormwood, the herb or shrub scientifically known as Artemisia Absinthium and called αψινθος (apsinthos) in Greek — hence the star named Wormwood of Revelation 8:11.
The English term wormwood has nothing to do with worms or wood, but rather with the word vermouth, which in turn probably has to do with wer (man, as in werewolf, man-wolf) and mod, from the widely attested PIE root med-, to measure (hence words like modus), heal (hence "medicine"), and advice (hence words like μηδεα, medea, counsel). Wormwood is a plant with aromatic leaves and a violently bitter taste and even fatally toxic when ingested in copious amounts, so why the ancient Europeans called it by this lofty name remains a mystery.
But wormwood is a member of the same family of Asteraceae — bearing starry flowers like daisies and dandelions — as lettuce and artichokes, and was found to deter insects and rodents, which may have helped secure is place in medicinal lore. Wormwood also drives away other plants, who evidently also can't stand its chemical signature, so farmers may have kept wormwood on the borders of their fields to repel pests, but made sure it wouldn't invade the fields to usurp the crops. All this appears to imply that wormwood may have seemed like the agricultural equivalent of what the dog was to shepherds — and see our articles on κυων (kuon), dog, and ποιμην (poimen), shepherd.
How the Hebrews arrived at their word for wormwood, לענה (l'ana), is also unclear (we'll get into that further below), but it's important that we remember that the Hebrews didn't name things according to their appearance or their families (or scientific classification), but rather by their signifying behavior. That means that "being bitter in certain way" was named first, and the plant who was found to behave bitterly in that way was named after it. Said otherwise: our Hebrew word does not correspond with a specific species of plant but rather with a specific species of activity. That means that where translations may appear to be deploying a metaphor involving a plant, in Hebrew there is no metaphor going on and the situation is described quite literally. The word does not primarily denote a plant. But when it does, our plant symbolized bitterness and that in a decidedly negative way:
Our noun לענה (l'ana), wormwood, occurs eight times in the Old Testament, in reference to the effects and consequences of idolatry (Deuteronomy 29:17, Jeremiah 9:15, 23:15), adultery (Proverbs 5:4), injustice (Amos 5:7), unrighteousness (Amos 6:12), and the suffering of wrongful derision (Lamentations 3:15, 3:19). Our word is often accompanied by the word ראש (rosh), meaning bitter (as in: water of bitterness, or a root bearing bitterness), and ראש (rosh) in turn is also applied to the "bitter" venom of serpents (Deuteronomy 32:33, Job 20:16). This word ראש (rosh) is identical to a ubiquitous word meaning head (top, chief, most important), as well as a verb that means to be disenfranchised, to have lost liberty and civil rights, usually due to poverty or conquest.
Note that these words לענה (l'ana), wormwood, and ראש (rosh), bitter, are never used positively. In that regard, they are entirely unlike semi-synonyms that derive from the root מרר (marar), to be bitter (although note the use of this verb in Lamentations 3:15). The latter describes the kind of bitterness that results in learning (hence the name Mary, the mother of the Logos; also see Genesis 3:16, Ecclesiastes 1:18) and liberty (hence the "bitter herb" of Pesah: Exodus 12:8, and the myrrh of the consummation of marriage). Paul, speaking about sorrow, points to a closely similar distinction: "For the sorrow that is according to the will of God produces a repentance without regret, leading to salvation, but the sorrow of the world produces death" (2 Corinthians 7:10).
As said earlier, it's unclear where our word comes from and chances are excellent that it is foreign. Native Hebrew words, as a rule, stem from roots that have three letters. Our word would stem from a root לענ (l-'-n), but that root does not occur anywhere in the Bible (there are no other words in the Bible that have these three letters as their skeleton). It doesn't even happen in all the Aramaic of the Talmud (and that's a whole lot of Aramaic). The nearest candidate (say Ernest Klein's etymological dictionary and BDB's lexicon) is an Arabic verb la'an, which means to curse. So that would work. It would make wormwood a [foreign] cursing one or cursed one.
However, Klein also notes the not dissimilar word לענית (lo'anit), which is modern Hebrew for the Scrophularia genus of plants (also a low herb or shrub), and proposes that word to derive from the noun לע (lo'a), meaning throat (Proverbs 23:2 only), from the verb לעע (la'a), to swallow down or to talk wildly or rashly. That would work too. And note Paul's play on Psalm 5:9 and 104:3: "Their throat is an open grave. With their tongues they keep deceiving. The poison of asps is under their lips" (Romans 3:13), and note the playful similarity between αψινθος (apsinthos) and ασπις (aspis), asp (a kind of snake).
Then, the letter ל (le) also serves as a very common prefix that means to or onto and may indicate a physical or mental motion toward, or a behavioral or evolutionary effort, or express determination or purpose. It may also introduce an infinitive, to express purpose or continuous action (like a gerund). The name of this letter, lamed, is also the word for cattle prod or goad. And that leaves us with ענה ('ana):
There are four verbs of the form ענה ('ana), which may actually be one and the same but with four specialized usages. The first one means to answer, respond or correspond. Noun עת ('et) means time. Noun מענה (ma'aneh) means answer and noun ענה ('ona) means cohabitation. The second identical verb means to be busy or occupied with. Noun ענין ('inyan) means occupation or task. Verb three means to afflict, oppress or humble, which comes close to the word ראש (rosh) we discuss above. Noun ענו ('anaw) refers to the poor, afflicted or needy, noun ענוה ('anawa) means humility, noun ענות ('enut) affliction, adjective עני ('ani) poor or afflicted, noun עני ('oni) affliction or poverty, and noun תענית (ta'anit) humiliation. The four identical verb means to sing, but is probably an extension of the first one (a much more common verb meaning to sing is שיר, shir).
And then there is the noun ענן ('anan), which means cloud in the sense of a thick obscuring pack (not an individual cloud). The identical verb ענן ('anan) has to do with some kind of forbidden occult practice (Leviticus 19:26). Since waters in the Bible are closely associated with peoples, their languages and cultures (see Revelation 17:15; also see our article on the name Tigris), clouds correspond to the uncharted undercurrents of society: nameless fashions whose consistency is too thin to be consciously noticed, but which may gather into darkness and storm, and ultimately break to pour out in life giving torrents (see our article on νεφελη, nephele, cloud).
Now, we're not saying that there is a technical, etymological connection between all these words, but we are saying that there is a poetic one. In antiquity, there were no dictionaries yet, and ancient people collective settled upon the word לענה (l'ana) because that word looked like it explained precisely what that plant did (whether autonomously or via the extended agent of some wielder or applier of these plants). When carefully curated, it could govern one's pumpkin patch and keep it free from skrewts and such, and in small doses, it could give a zingy taste to food or beverages. But when one lost control over it, it would wipe out one's pumpkins in a season, and make food inedible and toxic.
All things considered, it seems that in the Hebrew mind, wormwood may have symbolized the kind of vigilant satire that would keep one's community free from unwanted weirdos, but which in uncontrolled and copious amounts would morph into mad derision and ultimately fuel witch hunts and genocide.