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

obreption \obrep"tion\, n. l. obreptio, fr. obrepere,
   obreptum, to creep up to; ob see ob- + repere to creep.
   1. the act of creeping upon with secrecy or by surprise.
      obs. --cudworth.
      1913 webster

   2. scots law the obtaining gifts of escheat by fraud or
      surprise. --bell.
      1913 webster
see also:
ob- 

[2] : Bouvier's Law Dictionary, Revised 6th Ed (1856)

obreption, civil law. surprise. dig. 3,5,8,1. vide surprise. 

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