Concise Bible Dictionary:
The word commonly so rendered in the Old Testament is tebel, signifying “the habitable earth:” it is an expression of limited bearing, applied to that sphere which comes more directly under divine dealings (Psa. 90:2); and to the inhabitants, who will be judged (Psa. 9:8). The word in the New Testament answering to the above, is; οἰκονμέη its various applications can be seen (Luke 2:1; Acts 11:28; Acts 17:6, 31; Acts 19:27; Heb. 2:5). In the last passage it is the coming world, that is, that which is put under the Son of Man, that is spoken of.
In the New Testament κόσμος is the more general word, which in Greek writers signifies “order, regularity, ornament”; it is translated “adorning” (1 Pet. 3:3). The heaven and the earth, because of their order and beauty, are called cosmos, “the world.” This word is employed for “world” in its various meanings, as for instance the material earth (Rom. 1:20); the inhabitants of the world that will be judged (Rom. 3:6); and in a moral sense as the condition and spirit which is opposed to God (1 Cor. 2:12; James 4:4; 1 John 2:16).
Another word, αἰών, “age, duration,” is applied both to the present age, the course of this world, and to age-enduring, or eternity (Rom. 12:2; Gal. 1:4; Eph. 1:21; Eph. 6:12). With a preposition it is translated “forever,” and when the word is repeated, “forever and ever,” or “to the ages of ages” (2 Cor. 9:9; Gal. 1:5; Phil. 4:20; 1 Tim. 1:17). In two passages this word refers to the material worlds (Heb. 1:2; Heb. 11:3).
From Anstey’s Doctrinal Definitions:
This term is used in the New Testament in three main ways:
• As a PLACE—the planet Earth (John 1:10a; 9:5; 17:28; 18:37; Acts 17:24; Rom. 1:20; 1 Tim. 1:15; 1 John 4:17; Rev. 13:8).
• As a SOCIETY where Christ is excluded (John 8:23; 15:19; 17:14b-16, 18; Rom. 12:2; Gal. 1:4; 6:14; 2 Tim. 4:10; James 4:4; 1 John 2:15-17; 4:5a; 5:19). The world in this sense refers to the sphere of affairs and activities on earth which man in his alienation from God has arranged in an attempt to keep himself happy and satisfied without Christ. It operates on false principles and values, and is based on appealing to the desires of the flesh. The root principle that characterizes life in this sphere is self-seeking. Viewed in this sense, the world is a definite enemy of the Christian, which if it is allowed to have even a little space in a believer’s heart, will dethrone Christ from His rightful place there. The Christian overcomes this enemy by faith—by seeing Christ as the center of a whole other scene (1 John 5:4-5).
• As the PEOPLE who are part and parcel of the society that man has built for himself in his alienation from God (Psa. 17:14; John 1:10b; 3:16; 4:42; 6:51; 15:18; 17:14a; 1 John 4:5b, 14).