age, course, eternal, (for) ever(-more), (n-)ever, (beginning of the , while the) world (began, without end)

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).

Strong’s Dictionary of Greek Words:

from the same as 104; properly, an age; by extension, perpetuity (also past); by implication, the world; specially (Jewish) a Messianic period (present or future)
KJV Usage:
age, course, eternal, (for) ever(-more), (n-)ever, (beginning of the , while the) world (began, without end). Compare 5550