ETYM Old Eng. (h)abundaunce, abundance, French abondance, Latin abundantia, from abundare. Related to Abound.
The property of a more than adequate quantity or supply; SYN. copiousness.

The ratio of the total mass of an element in the earth's crust to the total mass of the earth's crust; expressed as a percentage or in parts per million

The ratio of the number of atoms of a specific isotope of an element to the total number of isotopes present