How do you differentiate the usage of "rock" in countable/uncountable form? Hello, I have a question about how native English speakers distinguish the usage of "rock" in countable or uncountable forms...Having check in my dictionary, the word rock has almost the same meaning in both forms. This question occurred when I was reading some reading material about Prometheus. There was some sentence describing his punishment in the Caucasus mountain. Below is the sentence. "Haughty as rock beneath his daily torment, believing that he suffered for the good of mankind he endured for years." In this sentence, almost all the nouns are defined with some articles, but rock is both countable and uncountable. As defined almost same in the dictionary, is "rock" part can be replaced as " the rock" because Prometheus must have been chained in one place so that there is the same rock beneath him... I would appreciate your help, comments, or any advice^^