This is not so much a Biblical term as a Biblical concept, although one Greek word for purpose should be noted: πρόθεσις, G4606, (Rom 9:11; Eph 1:11).
In the Bible, God has plans, or intentions, or purposes, and they are sure to triumph, at least finally (Prov 19:21). God had purposes that related to Egypt (Isa 19:17) and Assyria (14:26), as well as Israel.
In the first place, God created the world out of nothing (“Let there be,” Gen 1:3, etc.), through His will, so that the world did not emanate from His nature. Thus there is purpose in the creation of the world: “God saw that it was good” (1:12, 18, 21, 25). There is also purpose in man’s creation. Man was made “in his [God’s] own image” (1:27), and was to “fill the earth and subdue it; and have dominion over the...earth” (1:28).
After man’s sin, God purposed man’s redemption. There was a foregleam of this purpose in the protevangelium (3:15). God’s redemptive purposes were clear in His intention to “bless” Abram: “I will make of you a great nation” (12:2), He told the man from “ ” (11:31)—the man of faith and obedience.
In Old Testament times, God let it be known that the “sun of righteousness” would one day “rise with healing in its wings” (Mal 4:2)—a glory to Israel, and a light to lighten the Gentiles of the whole wide world (Isa 42:6). Of the prophets it may be said that Christ was “the master light of all their seeing.” The New Testament states, “To him [Christ] all the prophets bear witness that every one who believes in him receives forgiveness of sins through his name” (Acts 10:43). Besides, Jesus Himself, “beginning with Moses and all the prophets, interpreted to them in all the scriptures the things concerning himself” (Luke 24:27).
Whether God’s purposes are to be called decrees, as theology often has done, is a matter of opinion among Christians. Calvinists have tended to call the purposes decrees and to affirm a predestination of individuals that precedes those individuals’ response to God’s offer of salvation. Arminians often have avoided the term “decrees” (see Mildred Wyncoop, Fundamentals of Wesleyan-Arminian Theology , 127); and they have interpreted the predestination taught in such scriptures as Romans 9-11 and Ephesians 1-2 as speaking of God’s purpose to save the ones who repent and believe on Christ.
All would agree that God does have purpose, “For he has made known to us...the mystery of his will according to his purpose which he set forth in Christ as a plan for the fulness of time to unite all things in him,...according to the purpose of him who accomplishes all things according to the counsel of his will” (Eph 1:9-11).