Fausset's Bible Dictionary
An object of disgust (Leviticus 18:22); a detestable act (Ezekiel 22:11); a ceremonial pollution (Genesis 43:32); especially an idol (1 Kings 11:5-7; 2 Kings 23:13); food offered to idols (Zechariah 9:7). The Egyptians regarded it an abomination, i.e. ceremonially polluting, to eat with the Hebrew as foreigners (Genesis 43:32), because, as Herodotus says (Genesis 2:41), the cow was eaten and sacrificed by foreign nations. So when Pharaoh told Israel to offer sacrifice to Jehovah in Egypt without going to the wilderness, Moses objected: "we shall sacrifice the abomination of the Egyptians before their eyes" (the cow, the only animal which all the Egyptians held sacred), "and will they not stone us?" (Exodus 8:26) compare the Jews' own practice in later times (Acts 10:28).
The Hebrew, not only as foreigners, accounted by the intolerant mythology of Egypt as unfit for intercourse except that of war or commerce, but also as nomad shepherds, were an "abomination" to the Egyptians (Genesis 46:34). Therefore Joseph tells his brethren to inform Pharaoh, "Our trade hath been about cattle, both we and also our fathers," i.e. hereditarily; for Pharaoh would be sure then to plant them, not in the heart of the country, but in Goshen, the border land. The Egyptians themselves reared cattle, as Pharaoh's offer to make Joseph's brethren "overseers of his cattle" proves (Genesis 47:6), and as their sculptures and paintings show; but they abominated the nomad shepherds, or Bedouins, because the Egyptians, as being long civilized, shrank, and to the present day shrink, from the lawless predatory habits of the wandering shepherd tribes in their vicinity.
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Fausset, Andrew R. Entry for 'Abomination'. Fausset's Bible Dictionary. https://www.studylight.org/dictionaries/eng/fbd/a/abomination.html. 1949.