It is only in a part of their meanings that these two words are in any real sense synonymous, and it is that part which is here considered. Both A. V. and R. V. often translate αἰών by world, thus obscuring the distinction between it and κόσμος. αἰών is usually better expressed by age, it is the world at a given time, a particular period in the world's history. κόσμος has very frequently an unfavorable meaning, denoting the inhabitants of the world, mankind in general, as opposed to God. A similar meaning is often attached to αἰών, it means the spirit of the age, often in an unfavorable sense. See Ep. ii. 2, where both words occur together. An exceptional meaning for the plural of αἰών is found in Heb. i. 2 and xi. 3, where it denotes the worlds, apparently in reference to space rather than time.