Definitions of OS
  1. noun
    (computer science) software that controls the execution of computer programs and may provide various services
    synonyms: operating system
    see moresee less
    Microsoft disk operating system
    an operating system developed by Bill Gates for personal computers
    an open-source version of the UNIX operating system
    DOS, disk operating system
    an operating system that is on a disk
    UNIX, UNIX operating system, UNIX system
    trademark for a powerful operating system
    (trademark) an operating system with a graphical user interface
    type of:
    computer software, package, software, software package, software program, software system
    (computer science) written programs or procedures or rules and associated documentation pertaining to the operation of a computer system and that are stored in read/write memory
  2. noun
    the left eye
    synonyms: oculus sinister
    see moresee less
    type of:
    eye, oculus, optic
    the organ of sight
Word Family

Test prep from the experts

Boost your test score with programs developed by Vocabulary.com’s experts.

  • Proven methods: Learn faster, remember longer with our scientific approach.
  • Personalized plan: We customize your experience to maximize your learning.
  • Strategic studying: Focus on the words that are most crucial for success.


  • Number of words: 500+
  • Duration: 8 weeks or less
  • Time: 1 hour / week


  • Number of words: 500+
  • Duration: 10 weeks or less
  • Time: 1 hour / week