- Hydrology: The study of the movement and quality of water present on the Earth.
- Hydrography: The science of surviving and charting seas, rivers and lakes with special reference to their use for navigation.
- Hydrology: The study of water with reference to its occurrence and properties in the hydrosphere and atmosphere.
- Hydropathy: The cure of disease by the internal and external application of water.
- Hydroponics: The cultivation of plants by placing the roots in nutrient solutions rather than in soil.
- Lexicography: The writing or compiling of dictionaries.
- Limonology: It is the study of inland water.
- Linguistics: It is the study of human language.
- Macroeconomics: It studies the behavior of aggregate economy.
- Mammography: An X-ray technique of diagnosing and locating abnormalities of the breasts especially tumors.