infectious

Universal Words adjective 1 an infectious disease can be passed easily from one person to another, especially through the air they breathe: Flu is highly infectious. * (figurative) infectious laughter 2 [notusuallybeforenoun] if a person or an animal is infectious, they have a disease that can be spread to others: I'm still infectious. compareCONTAGIOUS infectiously adverb: to laugh infectiously