hitherto
adverb /ˌhɪðəˈtuː/
  /ˌhɪðərˈtuː/
(formal)- until now; until the particular time you are talking about迄今;直到某时 - a hitherto unknown species of moth迄今仍属未知品种的蛾 
- Her life hitherto had been devoid of adventure.迄今为止,她的生活没有冒险。 
 Collocations DictionaryHitherto is used with these adjectives:- impossible
- neglected
- unheard-of
- …
 
- a hitherto unknown species of moth