case-sensitive Requiring or making a distinction between upper- and lower-case letters. In any situation where a computer program is reading characters, a decision has to be made whether to treat upper- and lower-case letters the same or differently. In some cases, such as word processor or text editor input, case must be preserved, while when performing an alphabetic sort, case might be ignored. Passwords may or may not be case-sensitive, depending on the circumstances. In some areas there is no consensus; for example, UNIX commands are case-sensitive whereas MS-DOS commands are not.

case-sen·si·tive • adj. Comput. (of a program or function) differentiating between capital and lowercase letters. ∎  (of input) treated differently depending on whether it is in capitals or lowercase text.