In the Bible, a scapegoat is an animal that is ritually burdened with the sins of others, and then driven away. The concept first appears in Leviticus, in which a goat is designated to be cast into the desert to carry away the sins of the community.
And Aaron shall cast lots upon the two goats: one lot for the LORD, and the other lot for Azazel.-- Leviticus 16:8, Jewish Publication Society (1917)
Practices with some similarities to the scapegoat ritual also appear in ancient Greece and Ebla.
The word "scapegoat" is an English translation of the Hebrew '?z?zêl (Hebrew: ), which occurs in Leviticus 16:8. The Brown-Driver-Briggs Hebrew Lexicon gives la-azazel (Hebrew: ) as a reduplicative intensive of the stem '-Z-L "remove", hence la-'?z?zêl, "for entire removal". This reading is supported by the Greek Old Testament translation as "the sender away (of sins)". The lexicographer Gesenius takes azazel to mean "averter", which he theorized was the name of a deity, to be appeased with the sacrifice of the goat.
And Azazel taught men to make swords, and knives, and shields, and breastplates, and made known to them the metals of the earth and the art of working them, and bracelets, and ornaments, and the use of antimony, and the beautifying of the eyelids, and all kinds of costly stones, and all colouring tinctures.-- Enoch 8:1
Early English Christian Bible versions follow the translation of the Septuagint and Latin Vulgate, which interpret azazel as "the goat that departs" (Greek tragos apopompaios, "goat sent out", Latin caper emissarius, "emissary goat"). William Tyndale rendered the Latin as "(e)scape goat" in his 1530 Bible. This translation was followed by following versions up to the King James Version of the Bible in 1611: "And Aaron shall cast lots upon the two goats; one lot for the Lord, and the other lot for the scapegoat." Several modern versions however either follow the reading as a demon, Azazel, or footnote "for Azazel" as an alternative reading.
Jewish sources in the Talmud (Yoma 6:4,67b) give the etymology of azazel as a compound of az, strong or rough, and el, mighty, that the goat was sent from the most rugged or strongest of mountains. From the Targums onwards the term azazel was also seen by some rabbinical commentators as the name of a Hebrew demon, angelic force, or pagan deity. The two readings are still disputed today.
The scapegoat was a goat that was designated (Hebrew: ) la-'aza'zeyl; "for absolute removal" (for symbolic removal of the people's sins with the literal removal of the goat), and outcast in the desert as part of the ceremonies of the Day of Atonement, that began during the Exodus with the original Tabernacle and continued through the times of the temples in Jerusalem.
Once a year, on Yom Kippur, the Cohen Gadol sacrificed a bull as a sin offering to atone for sins he may have committed unintentionally throughout the year. Subsequently he took two goats and presented them at the door of the tabernacle. Two goats were chosen by lot: one to be "for YHWH", which was offered as a blood sacrifice, and the other to be the scapegoat to be sent away into the wilderness. The blood of the slain goat was taken into the Holy of Holies behind the sacred veil and sprinkled on the mercy seat, the lid of the ark of the covenant. Later in the ceremonies of the day, the High Priest confessed the intentional sins of the Israelites to God placing them figuratively on the head of the other goat, the Azazel scapegoat, who would symbolically "take them away".
In Christianity, this process prefigures the sacrifice of Christ on the cross through which God has been propitiated and sins can be expiated. Jesus Christ is seen to have fulfilled all of the biblical "types"--the High Priest who officiates at the ceremony, the Lord's goat that deals with the pollution of sin and the scapegoat that removes the "burden of sin". Christians believe that sinners who own their guilt and confess their sins, exercising faith and trust in the person and sacrifice of Jesus, are forgiven of their sins.
Since the second goat was sent away to perish, the word "scapegoat" has developed to indicate a person who is blamed and punished for the sins of others.
A concept superficially similar to the biblical scapegoat is attested in two ritual texts in archives at Ebla of the 24th century BC. They were connected with ritual purification on the occasion of the king's wedding. In them, a she-goat with a silver bracelet hung from her neck was driven forth into the wasteland of "Alini"; "we" in the report of the ritual involves the whole community. Such "elimination rites", in which an animal, without confession of sins, is the vehicle of evils (not sins) that are chased from the community are widely attested in the Ancient Near East.
Ancient Greeks practiced scapegoating rituals in exceptional times based on the belief that the repudiation of one or two individuals would save the whole community. Scapegoating was practiced with different rituals across ancient Greece for different reasons but was mainly used during extraordinary circumstances such as famine, drought, or plague. The scapegoat would usually be an individual of lower society such as a criminal, slave, or poor person and was referred to as the pharmakos, katharma or peripsima.
There is a dichotomy, however, in the individuals used as scapegoats in mythical tales and the ones used in the actual rituals. In mythical tales, it was stressed that someone of high importance had to be sacrificed if the whole society were to benefit from the aversion of catastrophe (usually a king or the king's children). However, since no king or person of importance would be willing to sacrifice himself or his children, the scapegoat in actual rituals would be someone of lower society who would be given value through special treatment such as fine clothes and dining before the sacrificial ceremony.
Sacrificial ceremonies varied across Greece depending on the festival and type of catastrophe. In Abdera, for example, a poor man was feasted and led around the walls of the city once before being chased out with stones. In Massilia, a poor man was feasted for a year and then cast out of the city in order to stop a plague. The scholia refer to the pharmakos being killed, but many scholars reject this and argue that the earliest evidence (the fragments of the iambic satirist Hipponax) show the pharmakos being only stoned, beaten, and driven from the community.
The dictionary definition of scapegoat at Wiktionary