As the vast majority of place names in the area are of Anglo-Saxon origin, the theory accepted by most philologists is that the name Croydon derives originally from the Anglo-Saxon croh, meaning "crocus", and denu, "valley", indicating that, like Saffron Walden in Essex, it was a centre for the cultivation of saffron.
It has been argued that this cultivation is likely to have taken place in the Roman period, when the saffron crocus would have been grown to supply the London market, most probably for medicinal purposes, and particularly for the treatment of granulation of the eyelids.

There is also a plausible Brittonic origin for Croydon in the form "Crai-din" meaning "settlement near fresh water" (Cf "Creuddyn" Ceredigion), the name Crai (variously spelled) being found in Kent at various places even as late as the Domesday Book.

Alternative, although less probable, theories of the name's origin have been proposed.
According to John Corbet Anderson: "The earliest mention of Croydon is in the joint will of Beorhtric and Aelfswth, dated about the year 962.
In this Anglo-Saxon document the name is spelt [here he uses Old English characters] Crogdaene.
Crog was, and still is, the Norse or Danish word for crooked, which is expressed in Anglo-Saxon by crumb, a totally different word.
From the Danish came our crook and crooked.
This term accurately describes the locality; it is a crooked or winding valley, in reference to the valley that runs in an oblique and serpentine course from Godstone to Croydon."
Anderson challenged a claim, originally made by Andrew Coltee Ducarel, that the name came from the Old French for "chalk hill", because it was in use at least a century before the French language would have been commonly used following the Norman conquest.
However, there was no long-term Danish occupation (see Danelaw) in Surrey, which was part of Wessex, and Danish-derived nomenclature is also highly unlikely.
More recently, David Bird has speculated that the name might derive from a personal name, Crocus: he suggests a family connection with the documented Chrocus, king of the Alemanni, who allegedly played a part in the proclamation of Constantine as emperor at York in AD 306.
As the vast majority of place names in the area are of Anglo-Saxon origin, the theory accepted by most philologists is that the name Croydon derives originally from the Anglo-Saxon croh, meaning "crocus", and denu, "valley", indicating that, like Saffron Walden in Essex, it was a centre for the cultivation of saffron. It has been argued that this cultivation is likely to have taken place in the Roman period, when the saffron crocus would have been grown to supply the London market, most probably for medicinal purposes, and particularly for the treatment of granulation of the eyelids.
There is also a plausible Brittonic origin for Croydon in the form "Crai-din" meaning "settlement near fresh water" (Cf "Creuddyn" Ceredigion), the name Crai (variously spelled) being found in Kent at various places even as late as the Domesday Book.
Alternative, although less probable, theories of the name's origin have been proposed. According to John Corbet Anderson: "The earliest mention of Croydon is in the joint will of Beorhtric and Aelfswth, dated about the year 962. In this Anglo-Saxon document the name is spelt [here he uses Old English characters] Crogdaene. Crog was, and still is, the Norse or Danish word for crooked, which is expressed in Anglo-Saxon by crumb, a totally different word. From the Danish came our crook and crooked. This term accurately describes the locality; it is a crooked or winding valley, in reference to the valley that runs in an oblique and serpentine course from Godstone to Croydon." Anderson challenged a claim, originally made by Andrew Coltee Ducarel, that the name came from the Old French for "chalk hill", because it was in use at least a century before the French language would have been commonly used following the Norman conquest. However, there was no long-term Danish occupation (see Danelaw) in Surrey, which was part of Wessex, and Danish-derived nomenclature is also highly unlikely. More recently, David Bird has speculated that the name might derive from a personal name, Crocus: he suggests a family connection with the documented Chrocus, king of the Alemanni, who allegedly played a part in the proclamation of Constantine as emperor at York in AD 306.
Croydon