Dictionary Definition:
Purā (indecl.) [Vedic purā; to Idg. *per, cp. Goth. faúr= Ags. for=E. (be -- ) fore; also Lat. prae=Gr. parai/=Sk. pare] prep. c. abl. "before" (only temporal) Vin iv.17 (purāruṇā=purā aruṇā before dawn); Sn 849 (purā bhedā before dissolution (of the body), after which the Suttanta is named Purābhedasutta, cp. Nd1 210 sq.; expld by sarīra -- bhedā pubbaŋ at SnA 549).