Definition

1. Adjective:
   • Capable of causing infection: Describes something, especially a disease or agent, that can be transmitted from one organism to another, invading and multiplying within the host.
   • Capable of spreading easily: Describes something, such as an emotion, behavior, or idea, that is readily communicated or transmitted from person to person.

Examples of Usage

• Adjective:
  • Influenza is a highly infectious respiratory illness.
  • Her enthusiasm was so infectious that soon everyone in the room was smiling.
  • The doctor isolated the patient to prevent the spread of the infectious agent.

Advanced Usage

• "infectious laughter": Laughter that is so genuine and cheerful it causes others to laugh as well.
  • His infectious laughter filled the hall and lifted everyone's spirits.
• "infectious disease": A disease caused by pathogenic microorganisms (like bacteria, viruses) that can be spread, directly or indirectly, from one person to another.
  • Vaccination is a key tool in controlling infectious diseases.

Variants and Related Words

• Infect (verb): To affect or contaminate with a disease-causing organism; to affect with one's feeling or idea.
  • The virus can infect the host's cells.
• Infection (noun): The process or state of being infected; the invasion and multiplication of microorganisms in body tissues.
  • The wound was cleaned to prevent infection.
• Infective (adjective): Synonymous with 'infectious' in the medical sense of being able to cause infection.
  • The patient was infective during the first week of illness.

Synonyms

• Contagious: Often used interchangeably with 'infectious' for diseases spread by direct or indirect contact; also used for emotions/behaviors.
• Communicable: (For diseases) Capable of being transmitted from one person to another.
• Catching: (Informal) Easily spread or transmitted.

Related Phrases

• Infectious period: The time during which an infected person can transmit the disease to others.
  • Patients are most contagious during the infectious period.
• Non-infectious: Not capable of being spread by infection; not caused by an infectious agent.
  • Arthritis is typically a non-infectious condition.

Related Idioms

• Spread like wildfire: To become known or disseminated very rapidly and uncontrollably, similar to how an infectious disease can spread.
  • The news of their victory spread like wildfire through the town.

Adjective

1. of or relating to infection
   • infectious hospital
   • infectious disease
2. easily spread; children catch it from their elders"- Bertrand Russell
   • fear is exceedingly infectious
3. caused by infection or capable of causing infection
   • viruses and other infective agents
   • a carrier remains infective without himself showing signs of the disease