infection
/ɪnˈfɛkʃən/noun
The spread of harmful germs multiplying out of control inside a person, animal, or plant.
'Infectious' spreads through air or water; 'contagious' spreads by touch. Laughter gets called both, but only figuratively.
Related words
diagnosisThe act, or an instance, of working out what illness or condition a person has and what is causing it.immuneUnable to catch a disease, either through natural resistance or because of vaccination.clinicA place where people receive medical care, especially patients who do not stay overnight.nutritionThe food and substances that a body needs to stay healthy and grow.acheTo feel a steady, dull pain, or to be the cause of such pain.wellnessThe state of being healthy in body and mind, sometimes covering safety as well.