| Garbology | Study of garbage | 
        
      | Gastroenterology | Study of stomach; intestines | 
        
      | Gastronomy | Study of fine dining | 
        
      | Gemmology | Study of gems and jewels | 
        
      | Genealogy | Study of descent of families | 
        
      | Genesiology | Study of reproduction and heredity | 
        
      | Genethlialogy | The art of casting horoscopes | 
        
      | Geochemistry | Study of chemistry of the earth's crust | 
        
      | Geochronology | Study of measuring geological time | 
        
      | Geogeny | Science of the formation of the earth's crust | 
        
      | Geogony | Study of formation of the earth | 
        
      | Geography | Study of surface of the earth and its inhabitants | 
        
      | Geology | Study of earth's crust | 
        
      | Geomorphogeny | Study of the origins of land forms | 
        
      | Geoponics | Study of agriculture | 
        
      | Geotechnics | Study of increasing habitability of the earth | 
        
      | Geratology | Study of decadence and decay | 
        
      | Gerocomy | Study of old age | 
        
      | Gerontology | Study of the elderly; aging | 
        
      | Gigantology | Study of giants | 
        
      | Glaciology | Study of ice ages and glaciation | 
        
      | Glossology | Study of language; study of the tongue | 
        
      | Glyptography | The art of engraving on gems | 
        
      | Glyptology | Study of gem engravings | 
        
      | Gnomonics | The art of measuring time using sundials | 
        
      | Gnosiology | Study of knowledge; philosophy of knowledge | 
        
      | Gnotobiology | Study of life in germ-free conditions | 
        
      | Graminology | Study of grasses | 
        
      | Grammatology | Study of systems of writing | 
        
      | Graphemics | Study of systems of representing speech in writing | 
        
      | Graphology | Study of handwriting | 
        
      | Gromatics | Science of surveying | 
        
      | Gynaecology | Study of women’s physiology | 
        
      | Gyrostatics | The study of rotating bodies |