Words / B1

in-FEKSH-uh-s/ɪnˈfekʃəs/

Infectious means a disease can spread: highly infectious; an infectious illness. Contagious is a close twin in everyday talk. Infectious can also describe a mood (infectious laughter). Infection is the noun. Do not call every illness infectious — a broken arm is not. Catching is informal for the disease sense.

Meaning

Able to spread from one person to another; also, of a mood, spreading easily.

Examples

• “Flu is highly infectious in crowded offices.”
• “Chickenpox is infectious before the rash is obvious.”
• “Her confidence was infectious in the revision group, which is the mood sense.”

Good to know

highly infectious. Close: contagious. Mood: infectious laughter. Not every illness. Informal: catching.

Near in meaning

contagious

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