Wordnet 3.0
ADJECTIVE (1)
1. 
 partially opaque; 
The Collaborative International Dictionary of English v.0.48:
Semiopaque \Sem`i*o*paque"\, a.
   Half opaque; only half transparent.
   [1913 Webster]
WordNet (r) 3.0 (2006):
semiopaque
    adj 1: partially opaque