The Isis is the name given to the part of the River Thames above Iffley Lock which flows through the city of Oxford. The name is especially used in the context of rowing at the University of Oxford. Historically, and especially in Victorian times, gazetteers and cartographers insisted that the river Thames was correctly named the River Isis from its source until Dorchester-on-Thames, where the river meets the River Thame and becomes the "Thame-isis" (from which the Latin (or pre-Roman Celtic) name Tamesis is derived), subsequently abbreviated to Thames; current Ordnance Survey maps still label the Thames as "River Thames or Isis" until Dorchester. However since the early 20th century this distinction has been lost in common usage outside Oxford, and some historians suggest the name Isis is nothing more than a contraction of Tamesis, the Latin name for the Thames.
A number of rowing regattas are held on the Isis, including Eights Week, the most important Oxford University regatta, in the Trinity term (summer), Torpids in the Hilary term (spring) and Christ Church Regatta for novices in the Michaelmas term (autumn). Because the width of the river is restricted at Oxford, rowing eights normally have a staggered start near Donnington Bridge and must then aim to "bump" the eight in front (i.e., catch up and touch or overlap with it sufficiently). The leading eight aims to "row over" (i.e., finish the race without being bumped).
The name Isis is also used for the second rowing crew of Oxford University Boat Club, who race against the second crew of the Cambridge University Boat Club, Goldie, before the annual Boat Race on the Thames in London.