Of a disease, easily transmitted to others.
“The flu was so contagious that everybody in town got sick!”
Of a fashion, laughter, etc., easily passed on to others.
“Wearing jeans was a contagious fad at that time.”
Of a person, having a disease that can be transmitted to another person by touch.
“They were highly contagious, spreading bacteria to other people.”
Transmitted from one person to another, usually through the air breathed.
“Cancer is not infectious.”
“More infectious diseases like the flu are usually less potent.”
Able to infect others.
“Despite feeling better, the patient is still infectious.”
Spreading quickly from one person to another.
“Her enthusiasm for work can be really infectious.”
Memorable and invoking excitement or interest.
“Pop music is more infectious than elevator music.”