malignant

malignant — adjective

1. A malignant tumour or disease is caused by cancer cells that grow without contro

1.adjectiveB2
Definition

A malignant tumour or disease is caused by cancer cells that grow without control and can spread to other parts of the body, often leading to serious health problems or death.

Example

The biopsy showed that the lump on Christopher's neck was malignant and required immediate surgery.

contrast with benign: malignant results trigger urgent treatment

Doctors removed a malignant tumour from Sayaka's lung before it could spread to nearby organs.

malignant + tumour = core medical collocation

Common collocations
  • malignant tumour
  • malignant growth
  • malignant disease
  • malignant cells
  • malignant melanoma
  • malignant cancer
Synonyms
  • cancerous

    more specific — directly naming the disease rather than describing its quality

  • terminal

    stronger — implies that death is certain and imminent, not merely likely

  • invasive

    focuses specifically on the ability to spread into surrounding tissues

Antonyms
  • benign

    direct opposite — a growth that is not cancerous and does not spread

Grammar Patterns

malignant + noun (tumour, growth, disease, cell)

be/become + malignant

Usage Note

This is the most common and primary meaning of 'malignant'. It is the direct opposite of 'benign'. The word appears most frequently in medical reports, diagnoses, and health contexts. When used without a noun, it almost always refers to a tumour or growth (e.g. 'The lump was malignant').

Common Mistakes

The doctor said the tumour was malignant cancer.
The doctor said the tumour was malignant.
'Malignant' already implies cancer; saying 'malignant cancer' is redundant.
She has a malignant fever.
She has a serious fever caused by an infection.
'Malignant' is not used for general illnesses; it is reserved for cancerous growths.

2. Used to describe a person's character, actions, or influence that show a deep an

2.adjectiveB2
Definition

Used to describe a person's character, actions, or influence that show a deep and active desire to cause harm, suffering, or destruction to others, rather than labelling the person themself.

Example

Emre's malignant gossip destroyed the trust that had held the office team together for years.

malignant + gossip = figurative use describing spiteful speech

President Defne's malignant policies forced thousands of farming families to leave their homes and flee across the border.

malignant + policies = figurative use describing state-sponsored harm

Common collocations
  • malignant influence
  • malignant intent
  • malignant pleasure
  • malignant spirit
  • malignant force
  • malignant gossip
Synonyms
  • malevolent

    nearly identical in meaning; slightly more literary and focused on wishing evil

  • malicious

    more common in everyday language; implies spite and the intention to hurt feelings or reputation

  • sinister

    describes something that seems threatening or evil, but may not actively cause harm

  • vicious

    emphasises violent or cruel behaviour rather than hidden intent

Antonyms
  • benevolent

    direct opposite — wishing to do good and help others

  • kind-hearted

    less formal opposite — naturally caring and generous

Grammar Patterns

malignant + noun (influence, intent, pleasure, spirit, force)

be/become/seem + malignant

Usage Note

This sense is formal and often appears in literary, political, or rhetorical contexts. For everyday situations describing minor ill will, 'malicious' or 'spiteful' are more common and natural. The medical sense (CANCEROUS GROWTH) is far more frequent in general use.

Common Mistakes

He gave me a malignant look when I took the last biscuit.
He gave me a nasty look when I took the last biscuit.
'Malignant' is far too strong for everyday annoyance; reserve it for deep, serious evil.

malignant — noun

Word family

  • malignancy
    nounC1
  • malignantly
    adverbC1
  • malign
    verbC2

Synonym discussion

Sense: adjective/2

While all four words describe harmful intent or behaviour, they differ significantly in intensity and scope. 'Malignant' (in its figurative sense) is the strongest — it describes a deep, active, almost pathological desire to destroy, often suggesting that the harm is part of someone's core nature. 'Malevolent' is very close in meaning but slightly more literary; it focuses on the wish for evil to befall others without necessarily acting on it. 'Malicious' is far more common in everyday language and describes deliberate spite aimed at hurting someone's feelings, reputation, or position — the harm is real but rarely life-threatening. 'Sinister' does not describe action at all; it refers to a threatening appearance or atmosphere that suggests hidden evil. 'Vicious' leans towards physical violence or verbal cruelty in the moment. For example: 'The dictator's malignant policies starved millions' (deep, systemic evil) vs 'Her malicious gossip ruined his reputation at work' (deliberate but smaller-scale hurt) vs 'He gave her a sinister smile' (threatening appearance only).

malevolentmalicious ↗sinister ↗vicious ↗

Common collocations

Nouns

Adverbs

  • highly malignant
  • truly malignant
  • potentially malignant
  • deeply malignant

Phrases

  • benign or malignant
  • malignant or benign
  • diagnosed as malignant

Etymology

LatinFrenchEnglish

The word 'malignant' comes from Latin 'malignus', meaning 'wicked by nature' — a combination of 'malus' (bad) and 'gnus' (born, produced). It entered English in the mid-16th century with the general meaning of 'disposed to do evil'. The medical sense, referring to cancerous growths that resist treatment and cause death, emerged in the 17th century as physicians observed that some tumours seemed to behave as if they had an 'evil nature' of their own. Modern medicine retains both the physical meaning (relating to cancer) and the figurative meaning (relating to evil intent).