'World' in the Bible

Which is come unto you, as it is in all the world; and bringeth forth fruit, as it doth also in you, since the day ye heard of it, and knew the grace of God in truth:

to whom it was His will to make known how vast a wealth of glory for the Gentile world is implied in this truth--the truth that 'Christ is in you, the hope of glory.'

Beware lest any man spoil you through philosophy and vain deceit, after the tradition of men, after the rudiments of the world, and not after Christ.

Wherefore if ye be dead with Christ from the rudiments of the world, why, as though living in the world, are ye subject to ordinances,

For you died [to this world], and your [new, real] life is hidden with Christ in God.

Conduct yourself with wisdom in your interactions with outsiders (non-believers), make the most of each opportunity [treating it as something precious].