An unwanted program running on a computer is called malware in general computer-security terminology.

Quick Scoop: What that means

  • “Unwanted program” usually refers to software you did not knowingly install, or that behaves in sneaky or harmful ways (showing ads, stealing data, slowing the system, etc.).
  • In many school/quiz contexts, the standard one-word answer to “An unwanted program running on a computer is called a ___” is malware.
  • More specific types of malware include:
    • Virus (infects and spreads via files)
    • Worm (spreads across networks)
    • Trojan (disguises itself as something legitimate)
    • Spyware/adware (tracks you or shows aggressive ads)

So if you’re answering a test or quiz, the safest single-word choice for “an unwanted program running on a computer” is: malware.

TL;DR: An unwanted program running on a computer is called malware.

Information gathered from public forums or data available on the internet and portrayed here.