Answer: Homosexuality (commonly referred to as being gay), as defined in the Bible, is sexual desire or intercourse directed toward someone of the same gender (Leviticus 18:22).
It should first be noted that the KJV Bible does not contain the words "homosexuality" or "gay" in its text. The word "gay" comes from the Middle English word "gai" which came into existence around 1275 to 1325 A.D. (dictionary.com). It originally meant something that was fast, sudden, merry or showy. The use of the word gay as a synonym for homosexuality began sometime around the late 1930s and 40s.
Your question about homosexuality, especially in regard to it as it applies to females, can be found in several places in the Bible. In Romans 1, the Apostle Paul states that women who change the natural use of sex with a man to intercourse between each other (just like men doing so) are in error or sin (verses 26 - 27). God treats both males and females the same regarding this behavior and condems all of it.
For this cause (people rejecting God exists even though proof of such existence is made plain to them), God also abandoned them to uncleanness through the lusts of their hearts, to disgrace their own bodies between themselves (homosexuality)
. . . For this cause, God abandoned them to disgraceful passions; for even their women changed the natural use of sex into that which is contrary to nature . . . (Romans 1:24, 26, HBFV).
In regard to this type of unacceptable behavior, the book of Jude clearly states that all those in Sodom and Gomorrah (men and women) were punished with the death penalty for indulging in "different" or "strange" flesh. This penalty came in the form of fire and brimstone, raining down from heaven upon the two cities, and burning everything up completely like the lake of Fire (Jude 7).
Why does God detest homosexuality? Paul, in the book of 1Corinthians (see 1Corinthians 15:42 - 49), reveals that the Eternal is reproducing Himself by creating spiritual sons and daughters. Our ultimate destiny, if we are willing and repent of our sins, is to be a part of the divine family. The purpose of marriage and sex, between a man and a woman, is to produce children that can also ultimately enter the Kingdom of God.
A lifestyle that centers around being gay works against God's great plan since procreation cannot occur between two people of the same sex. Homosexuality of any variation is confusion because God ordained reproduction through kind after its kind (Genesis 1).
In conclusion, the Bible defines and clearly states that homosexuality is forbidden and an abomination in the eyes of God (Leviticus 18:22, 20:13, 1Timothy 1:8 - 10). His judgment against those caught practicing this behavior was the death penalty (Genesis 19, Leviticus 20:13). Those who continuously indulge in the fulfillment of such lusts and do not repent will not be in the Kigdom of God (1Corinthians 6:9 - 11). Those who repent of their sinful ways, however, will be forgiven by God through Christ.