English. Janet is derived from Jane and was, at one time, an accepted diminutive for Jane. Its use as a given name was infrequent from the Middle Ages up to the late 19th century, except in Scotland where it has always been popular. The ultimate derivations is from Hebrew "God is gracious" via variants of John.
In Scotland, Jessie was originally a pet name for Janet. However Jessie is also a given name in its own right and these two names have been fully synonymous over two centuries. In earlier times Janet was also occasionally interchanged with Jean but these two names were not universally synonymous.
Some recent research into Scottish records [by AB] has shown that Jessie has been gaining in favour as a given name since its introduction in the mid-18th century. In the 1770s the ratio of Janet to Jessie baptisms in the I.G.I. was over 400:1. A century later the two names reached parity in the records. We would be interested to hear if anyone has a theory of why this change came about.
The 1841 Census of Aberdeenshire has several spelling variations, the most frequent of which are listed above. All should be found using Soundex searching.
Note that, as Jane [q.v.] is only very loosely linked to Jessie [q.v.], we have classed that link as a Lesser Synonym.
GCB has reported a tombstone in Banchory-Devenick, Kincardineshire, Scotland,which records:
"Erected by JOHN BREBNER in memory of his daughters. JEANNIE & JESSIE who died in infancy."
It is probable that these daughters were not alive at the same time so the second might have been named Janet in memory of her elder sister Jane, but unfortunately the parish records do not record the births.
Several correspondents [AB, JMcF, etc] have noted occurrences of a Jennie being baptised as Janet and JMacG, researching in Scotland, sent us a note recording
"... a legal document circa 1780 concerning a Janet, who undersigned Jennie".
CP has records of an ancestor, baptised Janet who was known as Nettie or Net, although this was not in official records. Other correspondents [C, MG, ML] have records of Jenny being used as a pet name for Janet, one in Berwickshire in the Scottish Borders.
AB has noted a number of recent examples of the use of Jinty as a nickname for Janet.
Note that Seònaid can be Anglicized as Seona or Shona and is the Gaelic form of Janet or the Irish Gaelic name Sinèad.
See also Jennet.