Jazz and brass band musicians refer to all wind instruments as horns. It's a colloquial term, not a technical one. If we were to go with the technical definitio

Jazz and brass band musicians refer to all wind instruments as horns. It's a colloquial term, not a technical one. If we were to go with the technical definition, trumpets and trombones wouldn't be considered horns either, because they have cylindrical bores instead of conical bores.