This unusual surname is of English medieval origins, although its derivation is French, and much earlier and probably pre 7th century. It derives from the word "dormeur" meaning "sleeper", and was introduced into England after the 1066 Norman-French invasion. It is or was a nickname for a heavy sleeper, or perhaps given the ribald humour of the medieval period, the reverse! We have not been able to identify any Chaucerian comments about "dormers" but no doubt there would have been some. Over 15% of British surnames are definately forms of nickname, indeed there are some researchers who are of the opinion that most surnames were at their creation, nicknames. The famous Victorian etymologist Canon Charles Bardsley also suggested that the name could be locational and derive from a place called Dormire, "mire" being a popular name suffix in the North of England, whilst "Dor" could refer to a river. He quotes that a Willelmus Dormire and an Agnes Dormire were recorded in the 1379 Poll Tax Rolls for Yorkshire, but he was unable to identify any place such as Dormire, and it seems likely that this was a localised spelling of Dormer/Dormour.The earliest known recording of the surname is probably that of Geoffrey Dormour, in the 1324 Subsidy Rolls for the county of Sussex. This was in the reign of King Edward 11nd of England, known as "Edward of Caernafon", 1307 - 1327.