F.A.
Hello, I have a friend who did not speak until he was 4 and then suddenly he decided to talk. He is now a very successful man who is in his early 40's and in fact speaks very well AND gives Public Speech classes! If I were you I would first bring it up with his pediatrician and see what he thinks. Do you have a list of all his words and when he said them? I kept track of all my sons new words in a journal. Kids do start talking at different ages. and it does not necessarily mean they have speech impediment. If the pediatrician recommends that you need to have a speech evaluation, then do it. There are so many times I have called the pediatrician to report something I have found abnormal and he has said: no that's ok, kids are different. I also have a niece who did not walk until she was 22 months old and they did all the tests and she was fine and is now a blossoming 18 year old who can walk, run, swim... no problem.
One more thing. Is your kid in a bilingual household? Sometimes, when kids are spoken to more than one language, they take a little longer to talk but then they start talking both languages at the same time. They are taking the time to assimilate. and you know, maybe if you take it easy on him, like not try to make him "say"the word and instead you just use the word, then he might not feel he is being forced to do something. Toddlers are smart little creatures, they want to take control and that's one very good way :-) Whenever I want to correct my 4 year old I just try to use the same word in a sentence that sounds as if I am just following the conversation so he doesn't think I am correcting him and usually he repeats it again correctly. Hope this helps. I would call the pediatrician and ask for his advice.