Where is the actual word wormwood mentioned in the Bible?

It does not appear any where, only ideas of what marriage is or atleast how it is seen by modern day Catholosism. The act of some type of marriage or union between individuals has been going on since before recorded time. The actual word "marriage" I believe is a 14th century English term.

Answer:

The first place "wormwood" appears is in Deuteronomy 29:18.

"Keep therefore the words of this covenant, and do them, that ye may prosper in all that ye do. Ye stand before the Lord your God... that He may establish thee to day for a people unto Himself, and that He may be unto thee a God, as He hath said unto thee, and as He hath sworn unto thy fathers, to Abraham, to Isaac, and to Jacob.

"Neither with you only do I make this covenant and this oath; but with him that standeth here with us this day before the Lord our God, and also with him that is not here with us this day: (For ye know how we have dwelt in the land of Egypt... and ye have seen their abominations, and their idols, wood and stone, silver and gold, which were among them:)

"Lest there should be among you man, or woman, or family, or tribe, whose heart turneth away this day from the Lord our God, to go and serve the gods of these nations; lest there should be among you a root that beareth gall and wormwood..." (Deut.29:9-18).

Wormwood: "la'anah" - from an unused root supposed to mean to curse; wormwood (regarded as poisonous, and therefore accursed):
KJV--hemlock, wormwood." (Strong's Definitions)

** The next place is Proverbs 5:4.

"...For the lips of a strange woman drop as an honeycomb, and her mouth is smoother than oil: but her end is bitter as wormwood [same as above], sharp as a two-edged sword." (Prov.5:3-4)

The "strange woman" referenced, of course, denotes "adultery"... but the context of the proverb speaks of God's "wisdom and understanding" -- the "strange woman" in this case meaning to depart from these "treasures" of God, which is the same as adultery in the Lord's eyes.

** The next place is Jeremiah 9:15. The House of Judah is being warned to return to the Lord's ways... and their captivity by Babylon is imminent.

"...they have forsaken My law which I have set before them, and have not obeyed My voice, neither walked therein; but have walked after the imagination of their own heart, and after Baalim, which their father taught them: therefore thus saith the Lord of hosts, the God of Israel; Behold, I will feed them, even this people, with wormwood [same word], and give them water of gall to drink. I will scatter them also among the heathen..." (Jer.9:13-16).

** Again in Jeremiah 23:15; Lamentations 3:15 & 19; Amos 5:7; and finally, Revelation 8:11.

"And the third angel sounded, and there fell a great star from heaven, burning as it were a lamp, and it fell upon the third part of the rivers, and upon the fountains of waters; and the name of the star is called Wormwood: and the third part of the waters became wormwood; and many men died of the waters, because they were made bitter." (Rev.8:10-11)

Here in the New Testament, the word is:

Wormwood: "apsinthos" - of uncertain derivation; wormwood (as a type of bitterness, i.e. [figuratively] calamity):
KJV--wormwood." (Strong's Definitions)

This sole "wormwood" referenced in the New Testament is the third of the seven "trumpet plagues" of the Day of the Lord that precedes Jesus' return [at the 'last trump'].