- communicable by infection, as from one person to another or from one part of the body to another: infectious diseases.
- causing or communicating infection.
- tending to spread from one to another: infectious laughter.
- Law. capable of contaminating with illegality; exposing to seizure or forfeiture.
- Obsolete. diseased.
Origin of infectious
SynonymsSee more synonyms for infectious on Thesaurus.com
1. See contagious.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for infectiously
He could be infectiously enthusiastic and extraordinarily charming: whenever we talked, his eye contact bordered on hypnotic.Is Steve Jobs Obsolete?
June 8, 2009
Zizi laughed outright, so infectiously, that Douglas joined in.The Come Back
Is there anything in life so infectiously joyous as a wagging tail?Balloons
They assembled themselves together of set purpose to be lively, and they were infectiously dismal.
Here in Christmas time you will witness many jolly and infectiously pleasant scenes.Christmas: Its Origin and Associations
William Francis Dawson
Under a soft panama hat a keen, shrewd face smiled so infectiously that the disgruntled seaman smiled back in spite of his grouch.Gold Out of Celebes
Aylward Edward Dingle
- (of a disease) capable of being transmittedCompare contagious
- (of a disease) caused by microorganisms, such as bacteria, viruses, or protozoa
- causing or transmitting infection
- tending or apt to spread, as from one person to anotherinfectious mirth
- international law
- tainting or capable of tainting with illegality
- rendering liable to seizure or forfeiture
Word Origin and History for infectiously
Online Etymology Dictionary, © 2010 Douglas Harper
- Capable of causing infection.
- Caused by or capable of being transmitted by infection.
- Caused by a pathogenic microorganism or agent.
- Capable of causing infection. See Note at contagious.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.