Ob- :: 
						 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-..