means Software written deliberately to damage, disrupt, or sneak into a computer or network — viruses, worms, ransomware, spyware, and their relatives.

from A late-20th-century blend coined as computer security became its own battlefield: 'mal-' (the Latin 'malus,' bad, the same gloomy root behind 'malice' and 'malfunction') bolted onto 'software.' The 'mal-' prefix had spent centuries flagging things gone wrong; here it simply moved into the machine.