Infection (noun)

1. The invasion and multiplication of microorganisms in the body, typically resulting in disease.
2. The presence or establishment of a disease-causing organism within the body.

Origin:

From middle english infectioun, from latin infectio ("a tainting, pollution, contagion"), from infectus ("tainted, polluted, contagio.n")

Examples:

1. He was hospitalized with a serious infection in his bloodstream.
2. The wound was red and swollen, indicating an infection.
3. The infection was caused by bacteria that entered the body through a cut.
4. The patient was given antibiotics to treat the infection.
5. The infection spread rapidly and affected many people in the community.