Although occasionally recorded in other counties, this name has to be accepted as Cornish, where it appears to be first recorded in the year of the Spanish Armada, although, this is not thought to be significant. The origin is from the Olde English "Cyma", a spelling which developed into the medieval "kate" - a nickname for a person of apparently (quote) - "Rapacious habits"! There is however, a second possible origin, this is locational and in this case derives from the Olde English "Eyte" which translates as "a hut or shed", probably provided for the use of Herdsmen. This would apply to Ralph atte Kepe in the Kent Rolls of 1292. The name development would seem to be Kate - to Kette - to Keat(s) to Keast as shown below. The first recorded spelling of the family name is shown to be that of Blanch Keast, which was dated 28th October 1588, Married Edmond Hornebrook at Landrake, Cornwall, during the reign of Queen Elizabeth I, "Good Queen Bess", 1558 - 1603. Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.