"in Chinese 牛逼"--->牛逼 in Chinese
"This word has become" better replaced with "it has become"
"old lady say"—> "old lady saying for accuracy"
"As a word, NIUBI牛逼 is made up of two single Chinese characters" (seems passive tone here not preferred)
"it's a noun in its origin" beter replaced with "it's noun in origin" for appropriateness.
"It has later evolved into many grmmatical categories" —>" It has later evolved to be of many other natures"
"in daily usage"—>" in daily use"
" how was your bull dick soup?"—> " How was the bull dick soup?"
"After you've read"—>"After you read"
loud"—>aloud"
There are some other minor ones in different categories. Anyway, it is a great niubi writing:) Congratulations.