Concise Bible Dictionary:
Scarlet—Carmine
The word most frequently translated “scarlet” is shani, and this is often accompanied by the word tolaath, “worm or grub,” apparently intimating that the color was obtained from some insect, as it is now from the cochineal.
Cochineal bugs on a prickly pear plant.
Scarlet was much used in the needlework and hangings of the tabernacle, in conjunction with blue and purple; but there it apparently refers to some fabric of the color of scarlet. If the purple be taken as symbolical of royalty and universal dominion, the scarlet may signify earthly grandeur and Israelitish royalty (Ex. 39:1-291And of the blue, and purple, and scarlet, they made cloths of service, to do service in the holy place, and made the holy garments for Aaron; as the Lord commanded Moses. 2And he made the ephod of gold, blue, and purple, and scarlet, and fine twined linen. 3And they did beat the gold into thin plates, and cut it into wires, to work it in the blue, and in the purple, and in the scarlet, and in the fine linen, with cunning work. 4They made shoulderpieces for it, to couple it together: by the two edges was it coupled together. 5And the curious girdle of his ephod, that was upon it, was of the same, according to the work thereof; of gold, blue, and purple, and scarlet, and fine twined linen; as the Lord commanded Moses. 6And they wrought onyx stones inclosed in ouches of gold, graven, as signets are graven, with the names of the children of Israel. 7And he put them on the shoulders of the ephod, that they should be stones for a memorial to the children of Israel; as the Lord commanded Moses. 8And he made the breastplate of cunning work, like the work of the ephod; of gold, blue, and purple, and scarlet, and fine twined linen. 9It was foursquare; they made the breastplate double: a span was the length thereof, and a span the breadth thereof, being doubled. 10And they set in it four rows of stones: the first row was a sardius, a topaz, and a carbuncle: this was the first row. 11And the second row, an emerald, a sapphire, and a diamond. 12And the third row, a ligure, an agate, and an amethyst. 13And the fourth row, a beryl, an onyx, and a jasper: they were inclosed in ouches of gold in their inclosings. 14And the stones were according to the names of the children of Israel, twelve, according to their names, like the engravings of a signet, every one with his name, according to the twelve tribes. 15And they made upon the breastplate chains at the ends, of wreathen work of pure gold. 16And they made two ouches of gold, and two gold rings; and put the two rings in the two ends of the breastplate. 17And they put the two wreathen chains of gold in the two rings on the ends of the breastplate. 18And the two ends of the two wreathen chains they fastened in the two ouches, and put them on the shoulderpieces of the ephod, before it. 19And they made two rings of gold, and put them on the two ends of the breastplate, upon the border of it, which was on the side of the ephod inward. 20And they made two other golden rings, and put them on the two sides of the ephod underneath, toward the forepart of it, over against the other coupling thereof, above the curious girdle of the ephod. 21And they did bind the breastplate by his rings unto the rings of the ephod with a lace of blue, that it might be above the curious girdle of the ephod, and that the breastplate might not be loosed from the ephod; as the Lord commanded Moses. 22And he made the robe of the ephod of woven work, all of blue. 23And there was an hole in the midst of the robe, as the hole of an habergeon, with a band round about the hole, that it should not rend. 24And they made upon the hems of the robe pomegranates of blue, and purple, and scarlet, and twined linen. 25And they made bells of pure gold, and put the bells between the pomegranates upon the hem of the robe, round about between the pomegranates; 26A bell and a pomegranate, a bell and a pomegranate, round about the hem of the robe to minister in; as the Lord commanded Moses. 27And they made coats of fine linen of woven work for Aaron, and for his sons, 28And a mitre of fine linen, and goodly bonnets of fine linen, and linen breeches of fine twined linen, 29And a girdle of fine twined linen, and blue, and purple, and scarlet, of needlework; as the Lord commanded Moses. (Exodus 39:1‑29); Josh. 2:18,2118Behold, when we come into the land, thou shalt bind this line of scarlet thread in the window which thou didst let us down by: and thou shalt bring thy father, and thy mother, and thy brethren, and all thy father's household, home unto thee. (Joshua 2:18)
21And she said, According unto your words, so be it. And she sent them away, and they departed: and she bound the scarlet line in the window. (Joshua 2:21); 2 Sam. 1:2424Ye daughters of Israel, weep over Saul, who clothed you in scarlet, with other delights, who put on ornaments of gold upon your apparel. (2 Samuel 1:24); Prov. 31:2121She is not afraid of the snow for her household: for all her household are clothed with scarlet. (Proverbs 31:21); Song of Sol. 4:33Thy lips are like a thread of scarlet, and thy speech is comely: thy temples are like a piece of a pomegranate within thy locks. (Song of Solomon 4:3); Isa. 1:1818Come now, and let us reason together, saith the Lord: though your sins be as scarlet, they shall be as white as snow; though they be red like crimson, they shall be as wool. (Isaiah 1:18)). In the New Testament they clothed the Lord in a scarlet robe, κὀκκινος (Matt. 27:2828And they stripped him, and put on him a scarlet robe. (Matthew 27:28)) it is “purple” in Mark and John: it may have been an old faded robe that could be called either. Scarlet is also employed with purple to point out the earthly grandeur of Papal Rome (Rev. 17:3-43So he carried me away in the spirit into the wilderness: and I saw a woman sit upon a scarlet colored beast, full of names of blasphemy, having seven heads and ten horns. 4And the woman was arrayed in purple and scarlet color, and decked with gold and precious stones and pearls, having a golden cup in her hand full of abominations and filthiness of her fornication: (Revelation 17:3‑4); Rev. 18:12,1612The merchandise of gold, and silver, and precious stones, and of pearls, and fine linen, and purple, and silk, and scarlet, and all thyine wood, and all manner vessels of ivory, and all manner vessels of most precious wood, and of brass, and iron, and marble, (Revelation 18:12)
16And saying, Alas, alas, that great city, that was clothed in fine linen, and purple, and scarlet, and decked with gold, and precious stones, and pearls! (Revelation 18:16)).