The term 'SCOTTISH CHIMNEY' is a reference to the traditional Scottish fireplace, which is a type of chimney that is built into the wall of a house. The term 'LUM' is a three-letter abbreviation for this type of chimney. It is a combination of the words 'LINTEL' and 'UMBRELLA, ' which refer to the two parts of the chimney. The LINTEL is the horizontal beam that supports the weight of the chimney, while the UMBRELLA is the curved top of the chimney.