Meaning of OPAQUE in English
/ əʊˈpeɪk; NAmE oʊ-/ adjective
( of glass, liquid, etc. ) not clear enough to see through or allow light through :
( of speech or writing ) difficult to understand; not clear
SYN impenetrable :
The jargon in his talk was opaque to me.
late Middle English opake , from Latin opacus darkened. The current spelling (rare before the 19th cent.) has been influenced by the French form.
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005