One source of German vocabulary confusion is nouns that can have more than one gender and more than one meaning. If you don't already know the difference between der See and die See, then you definitely need to look at this special glossary. But there are many other less obvious examples, including das/der Golf, der/die Leiter, or das/die Mark. See Confusing Genders in German
MORE: Confusing Word Pairs - Word sets that often get mixed up

WORT DES TAGES: German Word of the Day