confertisparsisonn.
Etymology: < Latin confertus crowded + sparsus sparse + sonus sound.Previous versions of the OED give the stress as: confertiˈsparsison.
Welsh Prosody.
1856 J. Williams tr. §200 A syllable that terminates with four consonants, having the obscure pronunciation of the mutescent y between each..is called confertisparsison.
This entry has not yet been fully updated (first published 1891; most recently modified version published online June 2019).