One book you should have is The Oxford Duden Italian Picture Dictionary. It has thousands of drawings and their names in English and Italian. There are also Duden picture dictionaries in French, German, Japanese, and Spanish.
The Italian one shows that un ombrello is an umbrella that you carry when it is raining or you are fighting Batman. Una ombrella is the umbrella shaped part of a jellyfish, una ombrella fioreta is a flower umbel, and una ombrella semplice is a simple umbel.