One of the five basic tastes. In English, Umami or Savory. According to Wikipedia, the word comes from the Japanese “umai (うまい) ‘delicious’ and mi (味) ‘taste’. The Chinese characters 旨味 are used for a more general meaning, when a particular food is delicious.”
When two or more foods caracterised with the umami taste are combined, the increase is exponential.
A super-umami combo you might like is tomato-spinach-mushroom.