What does "dangerous" mean?

1. (likely to cause harm) likely to cause physical harm, injury, or death. 2. (threatening or aggressive) describes a person or animal that is likely to attack or hurt others. 3. (critically ill) very sick and at risk of dying.

Is it correct to say "It is danger to swim here."?

No — say "It is dangerous to swim here.". Use the adjective 'dangerous' to describe a situation; 'danger' is the noun.

dangerous

adj.

US //ˈdeɪndʒɝəs// UK //dˈeɪndʒəɹəs// dan·ger·ous

1 likely to cause harm (adj.)
A1 Beginner

likely to cause physical harm, injury, or death.

involving or causing exposure to injury, pain, or loss. This is the primary sense used for physical hazards.

Example

It is dangerous to walk on the thin ice during the spring thaw.

Example

The mountain pass becomes exceptionally dangerous during the winter months when heavy snowfall obscures the narrow trail and increases the risk of avalanches.
Pitfall

It is danger to swim here.

It is dangerous to swim here.

Use the adjective 'dangerous' to describe a situation; 'danger' is the noun.
2 threatening or aggressive (adj.)
A2 Elementary

describes a person or animal that is likely to attack or hurt others.

characterised by a disposition to inflict harm or injury; often used to describe volatile individuals or aggressive animals.

Example

The police warned the public that the escaped tiger was very dangerous.

Example

The suspect was considered armed and dangerous, prompting the authorities to issue a high-level alert to all surrounding residential areas.
- gentle
- tame

Show 1 more senseShow fewer

3 critically ill (adj.)
C1 Advanced Formal Archaic Medicine

very sick and at risk of dying.

referring to a medical state where a patient's life is at immediate risk. This usage is increasingly rare in modern speech but remains in specific medical or literary contexts.

Example

The doctor said the patient's condition was dangerous after the long surgery.

Example

The bulletin released by the hospital confirmed that the prime minister remained in a dangerous state following the sudden cardiac event.
- critical
- terminal
- stable

Origin

From Middle English dangerous (“difficult, severe, domineering, arrogant, fraught with danger”), daungerous, from Anglo-Norman [Term?], from Old French dangereus (“threatening, difficult”), from dangier. Equivalent to danger + -ous. Displaced native Old English frēcne.