(a) [pred 作表语] firmly fixed or attached; secure 牢固; 坚固; 稳固的: The post is fast in the ground. 那柱子牢牢地埋在地里. * make a boat fast, ie moor it securely 把船系牢. (b) [attrib 作定语] (dated 旧) loyal; close 忠实的; 亲密的: a fast friend/friendship 忠实的朋友[牢不可破的友谊]. 
(of colours) not likely to fade or run （指颜色）不褪色的. 
(idm 习语) hard and fast => hard1.> fast adv
1 firmly; securely; tightly 牢固地; 稳固地; 紧紧地: be fast asleep, ie sleeping deeply 酣睡 * The boat was stuck fast in the mud. 那船深深地陷在泥里.
2 (idm 习语) hold fast to sth continue to believe in (an idea, a principle, etc) resolutely or stubbornly 坚持（某种思想﹑ 原则等）. play fast and `loose (with sb/sth) change one's attitude towards sb/sth repeatedly in an irresponsible way; trifle with sb/sth 对某人[某事物]反覆无常; 玩弄: Stop playing fast and loose with that girl's feelings can't you see you're upsetting her? 别玩弄那姑娘的感情--难道没看到你已经把她弄得心烦意乱了吗? stand `fast/`firm not retreat, change one's views, etc 不後退; 不让步; 坚定不移. thick and fast => thick.