Learner's definition of FIDELITY
the quality of being faithful to your husband, wife, or sexual partner
— often + to
the quality of being faithful or loyal to a country, organization, etc.
— usually + to
the degree to which something matches or copies something else
— + to
the degree to which a device (such as a CD player, radio, or television) correctly reproduces sounds, pictures, etc.
see also high fidelity