4. A single step or stage in the succession of natural descent; a rank
or remove in genealogy. Hence: The body of those who are of the same
genealogical rank or remove from an ancestor; the mass of beings living
at one period; also, the average lifetime of man, or the ordinary
period of time at which one rank follows another, or father is
succeeded by child, usually assumed to be one third of a century; an
age.
This is the book of the generations of Adam.
Gen. v. 1.
Ye shall remain there [in Babylon] many years, and for a long
season, namely, seven generations.
Baruch vi. 3.
All generations and ages of the Christian church.
Hooker.