heretofore before this time在这之前
同义词：so farthus farup to nowhithertoas yetyettil nowuntil now
ADV（副词） Heretofore means "before this time" or "up to now." 此前; 迄今 [美国英语][正式]
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。