Contagious
infectious, contagious, transferable, communicable, transmittable
catching. communicable. contractable. transmissible. transmittable. infectious
I believe the lay term would be contagious or catching. Meaning it can be passed from one person to another.
Some illegal drug users share needles
Since you posted your question in People & Relationships, I assume you are not asking about the word infectious in the context of communicable diseases! Are you referring to the word in the context of an infectious smile?In that sense it means attractive, fetching, or catching. An infectious laugh, however, could be one that is attractive, as a smile, or it could be one that is easily communicated -- much like an infectious disease is communicated from one person to another. tending to affect others, diseases, laughter,ideals.
It can be, when it means either "infectious" or "catchy" (infectiously popular).The word catching is the present participle of the verb "to catch." It can be a verb form, an adjective, or a noun (gerund).
Influenza is a highly infectious disease, even when the patient is recovering (unlike many other Infectious Diseases which quit being infectious when the patient begins to recover).
Mumps is an infectious disease.
SARS is an infectious disease.
Non infectious.
No, it is not infectious.