heretofore /ˌhɪətʊˈfɔː/ TEM8

• 1. 

  ADV Heretofore means "before this time" or "up to now." 此前; 迄今 [美国英语] [正式]

  例：

  They reported that clouds are an important and heretofore uninvestigated contributor to the climate.

  他们报告说，云是影响气候的一个重要因素，但迄今尚未进行过调查研究。