Wordnet 3.0
ADJECTIVE (2)
1. 
 added or derived from something outside; 
 not inherent; 
- Example: "an adscititious habit rather than an inherent taste"2. 
 supplemental; 
 not part of the real or essential nature of a thing; 
- Example: "adscititious vowels"
The Collaborative International Dictionary of English v.0.48:
Adscititious \Ad`sci*ti"tious\, a. [L. adscitus, p. p. of
   adsciscere, asciscere, to take knowingly; ad + sciscere to
   seek to know, approve, scire to know.]
   Supplemental; additional; adventitious; ascititious.
   "Adscititious evidence." --Bowring. -- Ad`sci*ti"tious*ly,
   adv.
   [1913 Webster]
WordNet (r) 3.0 (2006):
adscititious
    adj 1: added or derived from something outside; not inherent;
           "an adscititious habit rather than an inherent taste"
    2: supplemental; not part of the real or essential nature of a
       thing; "adscititious vowels"