octamer

oligomer \o*lig"o*mer\, n. (Chem.)
   A molecule composed of a small number of linked monomer
   units; a short polymer; -- compounds called oligomers have
   less than one hundred monomer units and usually less than
   thirty. Oligomers of increasing length are called {dimer},
   {trimer}, {tetramer}, {pentamer}, {hexamer}, {heptamer},
   {octamer}, {nonamer}, {decamer}, etc. In colloquial
   laboratory jargon, they may also be referred to as
   {nine-mer}, {ten-mer}, {eleven-mer}, {twelve-mer}, etc.,
   especially for oligomers of greater than eight units.
   [PJC]
    

octamer \oc"ta*mer\ ([o^]k"t[u^]*m[~e]r), n. [Octa- + Gr. me`ros
   part.] (Chem.)
   A molecule composed of eight monomer units bound to each
   other, usually in a linear array; as, an octamer formed from
   eight nucleotides is called an octanucleotide.
   [PJC]

   Note: An example of an octapeptide might be represented using
         the standard abbreviations for the component amino
         acids, e.g.: met-ala-ser-glu-lys-ala-val-gly
         An octanucleotide might be represented using the
         standard single-letter abbreviations for the component
         mononucleotides, e.g.: ATGCATGC.
         [PJC]