2 A sign or object that is used to mean something: s _ (n)
3 Interesting and different from others: o _ (adj)
4 Difficult to understand: c _ (adj)
7 Not difficult to do or to understand: s _ (adj)
8 Made or caused by nature and not by people or machines: n _ (adj)
9 To design or make something new: i _ (v)
10 The facts about why something happens or why someone does something: r _ (n)