From Longman Dictionary of Contemporary Englishsubdirectorysub‧di‧rect‧o‧ry /ˈsʌbdaɪrektəri, -də-/ noun (plural subdirectories) [countable] an area in a computer where files are stored inside another directory, in order to keep the files organized
Examples from the Corpus
subdirectory• Following the instructions in the WordPerfect manual, you created a subdirectory to contain the WordPerfect program.• This runs the batch file which will put you in the correct subdirectory and run the program.• This will execute a command in every subdirectory of a hard disk.• It doesn't really matter, as long as you end up with copies other than in the subdirectory which is about to be burned. 