The word “Thermometer” is derived from two words-thermo means ‘warm’ and meter means ‘to measure’. It’s a device which helps to measure temperature.it is not invented by a single person. Loads of modifications have been done on it and also the scientists are doing on it.If you want one type of thermometer for the whole family. However, if you intend to use it rectal, buy two thermometers and label them to distinguish which one is used for the rectal and which one is for the mouth. Never Use One Thermometer For Both Places.