'Generations' in the Bible

These are births of Noah: Noah is a righteous man; perfect he hath been among his generations; with God hath Noah walked habitually.

And God saith, 'This is a token of the covenant which I am giving between Me and you, and every living creature that is with you, to generations age-during;

'And I have established My covenant between Me and thee, and thy seed after thee, to their generations, for a covenant age-during, to become God to thee, and to thy seed after thee;

And God saith unto Abraham, 'And thou dost keep My covenant, thou and thy seed after thee, to their generations;

'And a son of eight days is circumcised by you; every male to your generations, born in the house, or bought with money from any son of a stranger, who is not of thy seed;