Attested: Ptolemy 2,3,6 Σιδουμανιου (or Ειδουμανιου) river mouth
Where: Ptolemy’s order of names and coordinates would fit one of the big estuaries in East Anglia, with Colne-plus-Blackwater more likely than Orwell-plus-Stour or Crouch-plus-Roach.
Name origin: The first element of Σιδουμανιου is like OE sid ‘wide, spacious, large’, from PIE *sē- ‘to sow, to spread out’, which survives as an adjective only in northern dialect, but it contributes to various place names, such as Sidestrand in Norfolk. Old Irish sith- ‘long’ might be cognate. The second element is related to Latin mano ‘to flow’ or μανος ‘loose’, from PIE *ma- ‘damp’. In Britain that element developed mainly towards marsh, leaving few clear parallels in river names (such as the Lincolnshire Witham, formerly Wiğma) and only debatable ones in place names (Manea, Manningtree, etc).
Notes: The lack of clear parallels in Celtic prompted R&S to propose a spelling **Eidumanis, traceable to misreading of Greek Sigma as Epsilon.
Last Edited: 17 July 2016