As a slang adjective, 牛 (niú) means 'awesome, impressive' — very colloquial, often for skills or coolness. 棒 (bàng) is a more general 'great, wonderful', while 厉害 (lìhai) emphasizes outstanding ability or intensity. Higher-level slang 神 (shén) and 猛 (měng) have stronger, more specific connotations.