Definition of Rouen lilac in English:

Rouen lilac

noun

  • A hybrid lilac, Syringax chinensis, which forms compact upright bushes and has narrow, pyramidal spikes of pink or purple flowers. [The Rouen lilac is believed to be the result of a natural hybridization between Syringa laciniata and the common lilac, S. vulgaris, at the Botanic Gardens in Rouen in the late 18th cent.]

Origin

Mid 19th century; earliest use found in John Loudon (1783–1843), landscape gardener and horticultural writer.