Citral is an acyclic monoterpene aldehyde, and being a monoterpene, it is made of two isoprene units. Citral is a collective term which covers two geometric isomers that have their own separate names; the E-isomer is named Geranial (trans-Citral) or Citral A. The Z-isomer is named Neral (cis-Citral) or Citral B.