1530, "goat sent into the wilderness on the Day of Atonement as a symbolic bearer of the sins of the people," coined by Tyndale from scape, a shortening of escape (see scape (v.)) + goat; the whole word translating Latin caper emissarius, itself a translation in Vulgate of Hebrew 'azazel (Leviticus xvi.8, 10, 26), which was read as 'ez ozel "goat that departs," but which others hold to be the proper name of a devil or demon in Jewish mythology (sometimes identified with Canaanite deity Aziz).
Jerome's reading was followed by Martin Luther (der ledige Bock), Symmachus (tragos aperkhomenos), and others (compare French bouc émissaire), but the question of who, or what (or even where) is meant by 'azazel is a vexed one. The Revised Version (1884) simply restores Azazel. But the old translation has its modern defenders:
Azazel is an active participle or participial noun, derived ultimately from azal (connected with the Arabic word azala, and meaning removed), but immediately from the reduplicate form of that verb, azazal. The reduplication of the consonants of the root in Hebrew and Arabic gives the force of repetition, so that while azal means removed, azalzal means removed by a repetition of acts. Azalzel or azazel, therefore, means one who removes by a series of acts. ... The interpretation is founded on sound etymological grounds, it suits the context wherever the word occurs, it is consistent with the remaining ceremonial of the Day of Atonement, and it accords with the otherwise known religious beliefs and symbolical practices of the Israelites. [Rev. F. Meyrick, "Leviticus," London, 1882]
The transferred meaning "one who is blamed or punished for the mistakes or sins of others" is recorded by 1824; the verb is attested by 1884. Related: Scapegoated; scapegoating.
For the formation, compare scapegrace (which is perhaps modeled on this word), also scape-gallows "one who deserves hanging," scapethrift "spendthrift" (mid-15c.).
1818, "a creeping motion, act of creeping," from creep (v.). Meaning "imperceptible motion" is by 1813 in reference to coal mines, 1889 in geology.
Meaning "despicable person" is by 1886, American English slang, perhaps from earlier sense of "a sneak" (1876). Creeper "a gilded rascal" is recorded from c. 1600, and the word also was used of certain classes of thieves, especially those who robbed customers in brothels. The creeps "a feeling of dread or revulsion" is first attested 1849, in Dickens.
Mission creep (1994) is American English, originally military, "unconscious expansion of troops' role in a foreign operation," and used especially in reference to the 1993 Battle of Mogadishu.
From the military perspective, the scapegoat for Somalia was "mission creep." We deployed for one discrete purpose and found ourselves employed for a multiplicity of other missions. This is naive. United States ground forces will likely never again deploy abroad without experiencing the demands of mission creep. [Ralph Peters, "Winning Against Warriors," in Strategic Review, summer 1996]