시원하다- cool; refreshing, soothing. Not necessarily cold (like in.. 60 degree weather for example..just cool, not really cold). This word is also used when you're drinking something cool like soda on a hot day. (And something weird is that korean people tend to say this when drinking hot things as well,the feeling of something hot in their throats is soothing I guess. But I digress) 춥다- Cold. (for example what you would feel in 20 degree weather. Freezing.) This word only applies to weather. 쌀쌀하다- Pretty cold, but not freezing. Only applies to weather 차갑다- Cold to the touch. (i.e when you touch an ice cube) Only applies to touch. 뜨겁다- Hot. Only applies to touch (like if you touch a stove top) 덥다- Hot. Only applies to weather (like 90 degree weather) 따듯하다.- Warm. Applies to both temperature and touch.