The aisling (Irish for 'dream, vision', pronounced [ˈaʃlʲɪŋ]), or vision poem, is a poetic genre that developed during the late 17th and 18th centuries in Irish language poetry. The word may have a number of variations in pronunciation, but the 's' of the first syllable is always realised as a [ʃ] ("sh") sound. Can also be spelled with a 'h' in between the s and l.