In the Bible, things that are lower down, or under, physically, generally represent things that are lower or more external spiritually. In some cases, the lower things have been separated and put away to protect the good, but in others, it can mean that a less exalted idea or good desire is supporting a more exalted one.

(References: Arcana Coelestia 4564 [1-2], 8610, 9656)

410. The name of the star is Wormwood, and a third of the waters became wormwood. (8:11) This symbolizes hellish falsity, the origin of their personal intelligence, by which they had falsified all the Word's truths.

The star symbolizes their personal intelligence owing to a conceit arising from a hellish love (no. 408). The name symbolizes its character (nos. 81, 122, 165). Wormwood symbolizes hellish falsity, which we will consider next. Waters symbolize truths (no. 50), here the Word's truths, because the subject is faith. A third means, symbolically, all, as said before. Gathering these into a single meaning yields the meaning presented above.

As for wormwood, it symbolizes hellish falsity because of its extreme bitterness, which renders foods and beverages unpalatable. Wormwood symbolizes such falsity, therefore, in the following places:

Behold, I feed... this people with wormwood, and will give them water of gall to drink. (Jeremiah 9:14-15)

...thus says Jehovah... against the prophets: Behold, I feed them with wormwood, and will make them drink water of gall; for from the prophets of Jerusalem hypocrisy has gone out into all the land. (Jeremiah 23:15)

...you turn justice into gall, and the fruit of righteousness into wormwood. (Amos 6:12, cf. 5:7)

...that there may not be among you a root bearing gall or wormwood. (Deuteronomy 29:18)

Since the Jewish Church falsified all the Word's truths, like the church which is the subject here, and the Lord represented it by all the events of His suffering, by permitting the Jews to treat Him as they had the Word, because He embodied the Word, therefore "they gave Him vinegar mingled with gall," which is like wormwood, "but when He had tasted it, He would not drink" (Matthew 27:34, Mark 15:23, cf. Psalms 69:21).

As that was the character of the Jewish Church, it is therefore described in this way:

He has filled me with bitterness, (and) He has made me drunk on wormwood. (Lamentations 3:15, 19)