Blood (Heb. dām). The essential fluid of human, animal, and even plant life (cf. Gen. 49:11–12; Deut. 32:14).
In addition to its literal meaning, blood can be interpreted figuratively as the equivalent of life itself. Thus, the “voice” of Abel’s shed blood cries from the ground for vengeance (Gen. 4:10). At Gen. 9:4–6 Noah is forbidden to eat flesh with “its life, that is, its blood,” either of animals or of human beings. The prohibition against eating animal flesh from which the blood had not been drained may have been to oppose a cruel, barbaric custom of eating live animals or those whose blood was still warm. 
Perhaps it implies the future importance of blood for sacrificial purposes. Human bloodshed was forbidden because human beings are created in the image of God (v. 6). When God demanded a reckoning for the blood of a human being, he took human life into his protection and established an intimate connection between blood and life. In this way God hoped to arrest the prevalence of murder spawned when Cain slew his brother Abel.
The Mosaic legislation did not alter this divine prohibition. The blood and the fat of animals were to be brought to the altar, to indicate that they belonged to God rather than to man. The priests could sprinkle the blood on the altar, but, like the other Israelites, could not eat it or the fat (Lev. 3:16–17; 7:22–27). Fat and blood offered upon the altar symbolized atonement and therefore belonged to God alone. During the wilderness period the slaughtering of a sacrificial “ox or a lamb or a goat” could be done only at the door of the tent of meeting (17:3–5). After the Conquest, however, the priests were permitted to sacrifice animals anywhere in Palestine, though they were still not permitted to eat animal blood (Deut. 12:15–16, 21–25; cf. 1 Sam. 14:34).
According to Lev. 17:11, God gave the blood of animals “upon the altar to make atonement for [the souls of his people]; for it is the blood that makes atonement, by reason of the life.” The slaughter had to take place on the altar and the sacrifice was to be given to the Lord. The express prohibition against eating animal blood was repeated and observed by the Jews (vv. 10, 12) and the sojourners (v. 13). The cultic significance of the shedding of animal blood reached its highest expression on the Day of Atonement, when the high priest brought it into the holy of holies and sprinkled it on the mercy seat (Lev. 16:14–15). As the essence of life, animal blood atoned for real life; symbolically, it atoned for the sins of the person making the sacrifice.
Myers, A. C. (1987). In The Eerdmans Bible dictionary (pp. 163–164). Grand Rapids, MI: Eerdmans.