[1] : The Collaborative International Dictionary of English v.0.48

obvention \obven"tion\, n. l. obvention, fr. obvenire to come
   before or in the way of, to befall; ob see ob- + venire
   to come: cf. f. obvention.
   the act of happening incidentally; that which happens
   casually; an incidental advantage; an occasional offering.
   obs. "tithes and other obventions." --spenser.
   1913 webster

         legacies bequeathed by the deaths of princes and great
         persons, and other casualities and obventions.
                                                  --fuller.
   1913 webster
see also:
ob- 

Obvention >> O Words
Obvention, definition of term: Obvention
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