This very interesting medieval English surname, recorded as Jaycock, Jeacock, Jecock, Jaycox, and Jaycocks, is a derivation of the French "Jacque" or the derivative Jack. These are both nickname forms of the personal name John , itself from the Hebrew "Yochanan", meaning "Jehovah has favoured me with a son". To this has been added the Olde English pre 7th century word "cock", which is believed to indicate (quote) "the pertness of lusty and swaggering youth". There are other explanations, given that the pre - medieval period was one renowned for its worldy approach to things natural and physical. The baptismal name as Jacque, John or Jack, became very popular after the 11th century crusades to free the Holy Land, and subsequently in all its many forms, the most popular of all surnames. The surname is first recorded in the early half of the 14th century, and examples include John Jecok, in the 1375 Court Rolls of the borough of Colchester, and John Jecokes in the 1381 Assize Court Rolls of the county of Warwickshire. Later developments included the marriage of Elizabeth Jeacock to John sharples at St. James Church, Clerkenwell, London in 1711. The first recorded spelling of the family name is believed to be that of William Jacok, which was dated 1327, in the "Subsidy Rolls of the county of Suffolk". This was during the reign of King Edward 111, known as "The Father of the Navy" 1327 - 1377. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.