English Reference
adjective · noun

malignant

adj. · n.
US /məˈɫɪɡnənt/ UK /məlˈɪɡnənt/ ma·lig·nant

  1. 01 C1 Advanced Technical Medicine

    adj.used to describe a tumour or disease that is cancerous and can spread to other parts of the body.

    adj.referring to a tumour that is invasive, tends to metastasize, and is likely to cause death if not treated.

    Simple

    The doctors were relieved to find that the growth was not malignant.

    In context

    Biopsy results confirmed that the cells were malignant, necessitating an immediate and aggressive course of chemotherapy to prevent further spread.

    Usage

    Usually used to describe tumours, growths, or diseases.

  2. 02 C2 Proficiency LiteraryFormal

    adj.having a strong wish to do harm or cause suffering to others.

    adj.characterised by intense ill will or a desire to cause deliberate harm; malevolent in nature.

    Simple

    The villain in the story had a malignant influence on everyone he met.

    In context

    The dictator's malignant presence was felt throughout the country, as his policies slowly dismantled the foundations of civil society.

    Teacher's tip

    In everyday English, 'evil' or 'harmful' are more common; reserve this for formal writing or describing a very deep, spreading kind of bad influence.

  3. 03 C2 Proficiency ArchaicFormal

    n.a person who is seen as dangerous or destructive to society.

    n.a person who is persistently hostile to a government or established authority; historically used for supporters of the king during the English Civil War.

    Simple

    The old records described the rebels as dangerous malignants.

    In context

    Parliamentary forces sought to identify and punish the malignants who had remained loyal to the crown during the uprising.

    rebelmalcontent

She was diagnosed with a fibrosarcoma – a malignant tumour – in her jaw, which was removed with surgery but later returned and began to invade her jawbone.

The Guardian· 21 Aug 2026

A benign but invasive canine oral cancer is often mistaken for a similar malignant one, leading to misdiagnoses in close to a third of cases.

Phys.org· 18 Aug 2026

From Middle French malignant, from Late Latin malignans. See malign.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Origin la-lat malignans
Level C1 · Advanced
Frequency Frequent
Updated