to contaminate (e.g. air or food) with an agent that causes disease
to pass on a disease or an agent that causes disease to (somebody or something)
said of a pathogenic organism: to invade (an individual or organ) and cause a disease
(usu + with) to transmit or pass on to (somebody) an emotion, laughter, etc
He infected us with his enthusiasm
said of a computer virus: to invade and damage (a system, program, file, etc)
to corrupt or taint (something)
infector noun
[Middle English infecten from Latin infectus, past part. of inficere to stain, from in-2 + facere to make, do]