Incubation period
Etymology
From Latin “incubare” (to lie upon or hatch), from “in-” (upon) and “cubare” (to lie down) — originally a bird brooding its eggs. Medicine borrowed the image: the disease sits quietly “hatching” inside the body before it emerges. The same root gives “incubator,” the warmed box where things develop out of sight.
noun phrase · /in-kyuh-BAY-shuhn PEER-ee-uhd/
The silent stretch between catching an infection and showing the first symptoms.
What it names
The dangerous gap in which a person is infected, often already contagious, yet feels and looks completely healthy — the reason diseases spread before anyone knows to be careful.
Example
Measles has a long incubation period, so by the time the rash appeared she had already unknowingly exposed her whole class.
Related idea
The incubation period ends when symptoms begin; a prodrome is the vague early phase — mild aches, malaise — after symptoms start but before the disease declares itself clearly. One is silence; the other is the first murmur.
See also