Software is basically a series of instructions that causes the PC to do something. The Operating System such as DOS is known as Systems Software. Application Programs such as a Word Processor or Spreadsheet perform the main tasks for which we use the PC i.e. a letter to Mum or managing the finances.
Meaning of SOFTWARE in English
English glossary of Internet and PC terminology. Английский глоссарий Интернет и ПК терминологии. 2012