1. (Science: genetics, microbiology) An individual who does not display the symptoms of a disease, but harbors the pathogen which causes it, or has the gene (or genes) for it, and can transmit the disease to others either through interacting with other individuals, or by passing the disease-causing gene (or genes) to offspring.
2. (Science: pharmacology) a substance which transports things, such as a carrier protein. A radio wave that can be modulated in order to transmit a signal.A person who has some pathogen to which he is immune but who can pass it on to others.Someone whose employment involves carrying something; the bonds were transmitted by carrier.An inactive substance that is a vehicle for a radioactive tracer of the same substance and that assists in its recovery after some chemical reaction.Pertaining to an organism that contains a genetic mutation which inherits disease, but does not express this phenotype due to the presence of a more dominant gene.