Eltoy, please don't ever use this word again, not in speech, and not in writing. I had no idea what it meant at all. People will think you are very strange if you call things saturnine. Draconian is fine though, a good word. Draconian restrictions, draconian policies, a draconian punishment, etc...

No, it's not a common word. It's _very_ rare. It's very "literary." It was used in the 1800s by very highly educated speakers writing for other educated speakers. I know the word but I wasn't sure what it meant until I looked it up. Don't try to use it. In the first place, most native English speakers will not know what it means. In the second place, never ever ever use a fancy word unless you are _sure_ you know what it means. [And it doesn't fit with "mood" or "look." It is something of a _permanent_ personality characteristic. He _is_ a saturnine individual, or he _has_ a saturnine disposition]. <---I was wrong about this. Enjoy it as a curious word with an interesting background (astrology), but don't use it. You can look it up if you read it in a book. Just for fun: in addition to the words named for planets--"mercurial," "jovial," "saturnine"--there are words named for the four humors: from blood, yellow bile, black bile, and phlegm, we get "sanguine," "choleric," "melancholy," and "phlegmatic."

In a comment, Eltoy responded: "There was an example of usage in Macmillan Dictionary, and this word was used with 'mood.'" Trust the dictionary. I was wrong about that. "I've faced with this word when I was reading The Dracula." I assume you mean "Dracula," by Bram Stoker. It was written in 1897. It confirms what I said: "It's very 'literary.' It was used in the 1800s..." "Dracula," and classic works of "English and American literature" like Dickens, Jane Austen, or Nathaniel Hawthorne are great literature but are not good models of modern English. If you read books from the 1800s you will learn a lot of advanced vocabulary and grammar. A change in written literary English happened sometime between World War I and II. Nowadays written English, even by the best writers, is plainer, simpler, and more like spoken English than it used to be.

The dictionary will tell you what the word means: http://www.merriam-webster.com/dictionary/saturnine => serious and unhappy (lower 50% of words) 1) It was a bad day. I'm in a saturnine mood now. 2) Tomas had a saturnine look as he watched his girlfriend sleep with ANOTHER guy. 3) Since she lost her dog, she's been in a saturnine mood. 4) I can't be saturnine after being dismissed. (I shouldn't be saturnine...) - I used this word in essays, but it was always replaced by other words. When do you use it? It is a "fancy-sounding" word used by writers in novels to add variety and intellectual content to their writing. We rarely use it in everyday speech, but you could if you wanted to. It's just a little formal. - Is it a less common word? Yes, lower 50% of words in use.

You are using the word correctly, however, I have NEVER heard anyone use this word. Maybe if I was very rich I would hear it more often haha. I would use more common synonyms like: blue, melancholy, down, gloomy, troubled, somber.