Picture books are a great way to introduce new vocabulary to young children. During the second and sequential readings of any great book I stop as I am reading to discuss a new word that may be unfamiliar to my students. I then use the word in several sentences, ask the students to use the word, and even act it out if the word lends itself to action.
Each school year, one of my favorite activities is building Vocabulary Books. After we have practiced a new word from our literature selection, I next ask the students to tell me the meaning of the word, using their own words. I then write the meaning on a sheet of paper and illustrate the word and its definition (modeled writing). I then send the students to gather their own Vocabulary Book, write the word, and draw a picture that represents the word. (As students are ready they can add the definition). At the end of the year the children take home their vocabulary book as a dictionary representing some of the words they have learned over the year.
For example, once we read a book by Joy Cowley that contained the word "fierce" and the children wanted to know what it meant. I asked them what they thought and they decided that (because of the context) the definition of fierce is "mean". After we finished the book and had our vocabulary discussion, the students recorded the new word in their Vocabulary Book.