noun
great plain; prairie; steppe; savanna; pampa
Refers to a vast, flat grassland. Can be used for specific geographical regions like the North American prairie, Eurasian steppe, African savanna, or South American pampa.
モンゴルの大草原を馬で駆け抜けた。
I galloped across the great plains of Mongolia on horseback.
アフリカ
Many wild animals inhabit the African savanna.
expression
Internet slang derived from the kanji 草 (grass) used to represent laughter. 大草原 intensifies the laughter, similar to 'LMAO' or 'ROFL'. See also 草 (sense 5).
See also: 草
あの動画、面白すぎて大草原だった。
That video was so funny, I was ROFL.
友達の冗談に大草原不可避。
I couldn't help but LMAO at my friend's joke.