1
: able to be passed from one person or animal to another by touching
a contagious disease
It's a highly contagious virus.
2
: having a sickness that can be passed to someone else by touching
I have a cold and I'm still contagious.
I'm sick, but the doctor says I'm not contagious.
3
: capable of being easily spread to others : causing other people to feel or act a similar way
She has a contagious smile. [=her smile makes other people smile; her smile makes other people happy]
contagious enthusiasm/laughter
Cite this Entry
“Contagious.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/contagious. Accessed 21 Jun. 2026.
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