contagious

adjectives

easily diffused or spread as from one person to another
"a contagious grin"
contagious
is derived from
contagion
is similar to
easily spread
"fear is exceedingly infectious; children catch it from their elders"- Bertrand Russell
infectious
(of disease) capable of being transmitted by infection
catching, communicable, contagious, contractable, transmissible, transmittable
is derived from
contagion
is derived from
contagion