Talk to your child constantly. Children learn language and increase their vocabulary in only one way — listening to the people around them. The richer and more abundant the language they hear daily, the more well developed their own language will be. In addition to normal conversation, however, you have dozens of creative and enjoyable ways to increase your child's vocabulary that can also build family bonds and heighten family fun.
Read aloud. Of course, you've been reading aloud to your child since he was born, but try reading books with characters and plots. Take time for discussion and point out new words and concepts to your child.
Show and tell. Whenever you go somewhere, collect something to bring back. Have a show-and-tell time when the family is together. Give your child the floor to tell about his treasure. These special objects need not be expensive or elaborate. The important part is sharing information and experiences.
Talk. Never underestimate the importance of good conversation and information to the development of vocabulary.
Label, label, label. Give your children as much vocabulary as you can. They will probably remember the big words most easily because shorter words with similar letters such as "was" and "saw" and "which" and "when" are confusing. Most preschoolers know all the names of dinosaurs that most adults can barely pronounce. Their minds are like sponges.
Use a variety of words to describe things; don't just use "good" and "nice." Take each new experience you have as an opportunity to learn new words. When you visit the auto shop to get a new muffler, talk about mufflers, tail pipes, exhaust systems, and welding. When you visit the greenhouse to choose new plants for the garden, talk about marigolds, impatiens, zinnias, and geraniums. When you make a new recipe, talk about woks, peanut oil, soy sauce, bean sprouts, water chestnuts, and pea pods.