1. ob- a prefix meaning “toward,”“to,”“on,”“over,”“against,” occurring in loanwords from Latin; used also, with the senses “reversely,”“inversely,” to form New Latin and English scientific terms: object; obligate; oblanceolate.
Etymology: (ME (< OF) < L, repr. ob (prep.); in some scientific terms, < NL, L ob-)
Definition of 'ob-'
Webster Dictionary
1. ob- a prefix signifying to, toward, before, against, reversely, etc.; also, as a simple intensive; as in oblige, to bind to; obstacle, something standing before; object, lit., to throw against; obovate, reversely, ovate. Ob- is commonly assimilated before c, f, g, and p, to oc-, of-, og-, and op-
Definitions of ob- 
