1. absurd; unreasonable; ridiculous
むっちゃ is dialectal
無茶な要求だった。It was an unreasonable demand.
2. rash; reckless
もう、あんな無茶はしないから。I won't do anything that reckless again.
3. excessive; immoderate; extreme
無茶なダイエットは体に良くない。Extreme diets are bad for your health.
4. very; extremely; excessively