ICC Profile
A standardised data file describing how a device's colour numbers relate to absolute, measurable colour.
In depth
Profiles are the translation layer that makes colour management possible: a camera or scanner profile says what the numbers mean, a monitor profile says how to display them correctly, and a printer profile says how to convert them for a specific paper and ink combination. Without profiles, colour numbers are only device instructions rather than descriptions of colour.
Examples in practice
A profile made for one paper and printer combination produces visibly wrong colour if applied to a different paper.