infectious

/ɪnˈfɛkʃəs/

/ɪnˈfɛkʃɪs/

Infectious means able to be spread by infection, like a disease that spreads from one person to another. You'll be uncomfortable shaking Uncle Marvin's hand if you're worried that warts are infectious.

Something that's infectious spreads easily, like infectious cold germs that might be left on a door handle — anyone who touches it might get sick. If your mother tells you the cut on your knee looks infectious, you'd better go to the doctor. Some infectious things are good — like infectious laughter that gets the whole class giggling, or your friend's infectious good mood that makes you forget your cares.

Definitions of infectious

1. adjective

   of or relating to infection
   “infectious hospital”

   “infectious disease”
2. adjective

   caused by infection or capable of causing infection
   synonyms: infective

   infected, septic

   containing or resulting from disease-causing organisms
3. adjective

   easily spread
   “fear is exceedingly infectious”

   synonyms:

   catching, communicable, contagious, contractable, transmissible, transmittable

   (of disease) capable of being transmitted by infection

   contagious

   easily diffused or spread as from one person to another

   contaminating, corrupting

   that infects or taints

   antonyms:

   noninfectious

   not infectious

   noncommunicable, noncontagious, nontransmissible

   (of disease) not capable of being passed on