In Gaeilge (Irish Gaelic) and the related Scottish Gaelic, 'Mc' and 'Mac' mean 'son of', so it functions the same way that the 'son' ending does in many Germanic languages. The Irish and Scottish languages are a form of Celtic known as Goidelic branch of the Celtic languages, distinct from the the Brittonic/Brythonic languages of Wales, Cornwall and Brittany. Brittonic are often called "P" Celtic as opposed to Goidelic 'Q' because of an early consonant shift that turned the Brittonic "P" sounds into a 'Q' i.e. 'K' sounds. Thus, in older forms of Welsh, the designation for 'son of' was 'Map' with the 'p' taking the place of the Goidelic 'c' - pronounced with a hard 'k' sound. In Welsh, the 'm' disappeared, so that to designate a father-son relationship, one would hear 'John ap John', John the son of John. One also hears in Welsh and Cornish regions an 's' patronymic device, meaning that an 's' is added to a first name to indicate paternity. Thus, John Williams means 'John son of William. Famously - and thanks to a Welsh accent, 'Johns' meaning son of John (one of the most common male names in Wales) was pronounced 'Jones' meaning son of John.