R.CH:CH.CO-

from The Collaborative International Dictionary of English v.0.48
acrylic \a*cryl"ic\ ([.a]*kr[i^]l"[i^]k), a.
   1. (Chem.) Of or containing acryl, the hypothetical radical
      ({R.CH:CH.CO-}) of which acrolein ({H2C:CH.CHO}) is the
      hydride; as, acrylic acid. The characteristic residue in
      an acrylic compound is the carbonyl group attached
      directly to an ethylenic carbon.
      [1913 Webster +PJC]

   2. Of or pertaining to a derivative of acrylic acid, or an
      object consisting mostly of an {acrylic resin}; as, an
      acrylic window.
      [PJC]
    

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