a prefix occurring originally in loanwords from Latin, where it meant "before" ( preclude; prevent ); applied freely as a prefix, with the meanings "prior to," "in advance of," "early," "beforehand," "before," "in front of," and with other figurative meanings ( preschool; prewar; prepay: preoral; prefrontal ).
Also, prae- .
[ prae-, prefixal use of prae (prep. and adv.); akin to FIRST, FORE, PRIOR, PRO 1 ]