fecundity
Concise Oxford English Dictionary © 2008 Oxford University Press:
fecund /ˈfɛk(ə)nd, ˈfiːk-/
▶adjective producing or capable of producing an abundance of offspring or new growth; highly fertile.
– derivatives
fecundity /fɪˈkʌndɪti/ noun.
fecundity /fɪˈkʌndɪti/ noun.
– origin ME: from Fr. fécond or L. fecundus.
'fecundity' also found in these Oxford entries:

