Refers to the treeless Arctic biome. Used in geography, ecology, and travel contexts.
from Russian
The tundra region of Siberia is vast.
sharp and sarcastic without acting lovestruck
Manga/anime slang; a pun on ツンデレ, describing a character who is always harsh and never shows a soft side. Used as a な-adjective or noun.
See also: ツンデレ
That character is totally tundra (always sharp, never lovestruck).