hitherto

副词 hitherto:

1. used in negative statement to describe a situation that has existed up to this point or up to the present time
   同义词：so far, thus far, up to now, heretofore, as yet, yet, til now, until now

1. In the execution of a computer program, to load a segment of the computer program in a storage area hitherto occupied by parts of the computer program that are not currently needed.
   在计算机程序执行中，把一个计算机程序段装入在此以前被当前不需要的程序部分所占用的存储器区域中。参阅formoverlay。
2. This is a fact hitherto unknown.
   这是一个至今无人知道的事实。