contagious
/kənˈteɪdʒəs/adjective
Spreading easily from one person to another.
Example sentences
- “Chickenpox is highly contagious among young children.”
- “The flu is most contagious during the first few days of symptoms.”
Laughter, enthusiasm, and yawns all get called contagious. Strictly, contagious diseases spread by contact, while 'infectious' covers other routes too.