Is there a characterisation for conjugated dienes similar to cis-trans?
The current version of Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book) supports various stereodescriptors that are used to denote specific conformers, in particular concerning conjugated dienes:


  P-94.3.1.3 Stereodescriptors s-cis and s-trans
  
  The spatial arrangement of two conjugated double bonds about the intervening single bond is described as ‘s-cis’ if ‘synperiplanar’ and ‘s-trans’ if ‘antiperiplanar’. This descriptor should not be applied to other systems such as N-alkyl amides (use ‘E/Z’ or ‘sp/ap’).