The Collaborative International Dictionary of English v.0.48:

macromolecule \mac`ro*mol"e*cule\, n. (Chem., Biochem.)
   A very large molecule, especially a polymer having from
   hundreds to many thousands of atoms, such as DNA, RNA,
   protein, polysaccharide, polyethylene, polycarbonate,
   etc.
   [PJC]

WordNet (r) 3.0 (2006):

RNA
    n 1: (biochemistry) a long linear polymer of nucleotides found
         in the nucleus but mainly in the cytoplasm of a cell where
         it is associated with microsomes; it transmits genetic
         information from DNA to the cytoplasm and controls certain
         chemical processes in the cell; "ribonucleic acid is the
         genetic material of some viruses" [syn: ribonucleic acid,
         RNA]