lol — written as the word for "grass".
Pure written slang: 草 at the end of a message means that was funny. 大草原 ("vast grassland") is the bigger version, like crying-laughing. Extremely common on X, YouTube comments and streams.
Laughter was typed 笑, then w, then wwww — which looks like a row of grass. So people started writing 草 instead.
Written only. Saying 草 out loud to mean "lol" is a joke in itself, not normal speech.
Reading a definition isn't the same as saying it to someone. Lingo Kaiava is a voice tutor set to Japanese — it uses 草 the way locals do, corrects you in the moment, and never "fixes" the way real people actually talk into textbook Japanese.
Free to start. No signup for your first conversation.