ENGLISH
REFERENCE

virus

n.
US //ˈvaɪɹəs// UK //vˈaɪɹəs// virus
  1. 1 biological germ (n.)
    A2 Elementary Science

    a tiny living thing that enters your body and can make you sick.

    a submicroscopic infectious agent that replicates only inside the living cells of an organism.

    Example

    The doctor said my sore throat was caused by a common virus.

    Example

    Researchers are studying how the virus mutates when it moves from animal hosts to human populations.

  2. 2 illness (n.)
    B1 Intermediate Informal Medicine

    a sickness or infection caused by a virus.

    an illness or medical condition resulting from a viral infection.

    Example

    I missed three days of work because of a stomach virus.

    Example

    The school reported a high number of absences this week due to a seasonal respiratory virus circulating among the students.

Show 2 more sensesShow fewer
  1. 3 malicious software (n.)
    B1 Intermediate Computing

    a harmful computer program that can copy itself and damage your files.

    a piece of code which is capable of copying itself and typically has a detrimental effect, such as corrupting the system or destroying data.

    Example

    Never click on suspicious links or you might get a virus on your laptop.

    Example

    The company's security software detected a sophisticated virus that was attempting to encrypt sensitive financial records.

  2. 4 harmful influence (n.)
    C1 Advanced Literary

    something bad or dangerous that spreads quickly from person to person.

    a harmful or corrupting influence that spreads rapidly within a group or society.

    Example

    Hatred can spread like a virus through a community.

    Example

    The orator warned that misinformation was a virus threatening the very foundations of their democratic institutions.

Origin

From Middle English virus, from Latin vīrus (“poison, slime, venom”), via rhotacism from Proto-Italic weizos, from Proto-Indo-European wisós (“fluidity, slime, poison”). First use in the computer context by David Gerrold in his 1972 book When HARLIE Was One.

© 2026 English Reference