The definition of blow-by-blow is told with a lot of details.
An example of a something told blow-by-blow is a story about a vacation that tells every single detail of what happened during the trip.
told in great detail: a blow-by-blow account of a debate
Origin of blow-by-blowused origin, originally with reference to an account of a boxing match
Exhibiting great detail: a blow-by-blow description of the accident.