Recorded in various spellings including Grimsdale, Grimsdell and Grinsdale, this is an English surname. It is locational from the village of Grinsdale in the county of Cumberland, on the border with Scotland. The name is believed to mean what it more or less says, which is green valley, from the Olde English pre 7th century "gren-dael". First recorded in the year 1188 as Grennesdale, and a century later in 1279 as Gremesdale, it is easy to see why the resulting surname itself has various spellings in which the letters "m" and "n" are almost interchangeable. In addition at this medieval time surnames were in the process of creation and the language itself was begining to enter the process which would lead to the creation some centuries later, of Standard English, more or less as we know it today. Locational surnames are usually "from" names. That is to say names that were either those of the local lord of the manor and his descendants as may be the case here, or they were given to people as easy identification, after they had left their origin homes to move somewhere else. In this case the earliest known recording is probably that of Adam de Grimisdale, who appears in the Subsidy Tax rolls of the county of Cumberland in the year 1332.