From the Greek "tropos" meaning "turn" or "direction":
* Tropic: A parallel of latitude, 23.5 degrees north or south of the equator, marking the limits of the sun's overhead position.
* Tropical: Relating to or characteristic of the tropics, often implying warm climates and lush vegetation.
* Tropism: The turning or bending of a plant or other organism in response to an external stimulus, such as light or gravity.
* Phototropism: The growth of a plant in response to a light stimulus.
* Geotropism: The growth of a plant in response to gravity.
* Hydrotropism: The growth of a plant in response to water.
* Thigmotropism: The growth of a plant in response to touch.
* Troposphere: The lowest layer of the Earth's atmosphere, where weather occurs.
Other words with the "tropic" root:
* Tropic bird: A seabird with long, narrow wings and a distinctive long, central tail feather.
* Tropicália: A Brazilian artistic and cultural movement of the 1960s that blended traditional Brazilian music with modern influences.
* Tropics: (Plural) The region of the Earth between the tropics of Capricorn and Cancer.
* Tropopause: The boundary between the troposphere and the stratosphere.
Let me know if you'd like more examples or explanations!