This unusual and interesting surname is English. It is medieval, but of pre 7th century Olde English origins. It is or rather was, almost certainly a nickname for 'the son of a bit of a lad'. The derivation is from the word 'chitte' meaning a cub or calf, and -ock, a short or fused form of the ancient word 'cocca' meaning a son. Nicknames were very popular in medieval times, and were often at the very least robust, and sometimes obscene, as can be shown by a perfunctory study of the works of Geoffrey Chaucer. However such as we are able to tell, our ancestors did not seem to see them in that light, and certainly do not seem to have objected. One could say that this particular name has survived because it is quite harmless in meaning, whilst others have been gentrified over the centuries, to the point where the original spelling is totally lost. At least fifteen percent of all surnames have a nickname base, although many researchers believe it to be much higher. Early examples of the surname recording are those of Roger Chittok in the Hundred Rolls of the county of Huntingdon in the year 1279, and Henry Chittock who appears in the Tax Subsidy Rolls of the county of Sussex in 1332.