He's now doing his own adaptation of the sign for book by clapping his hands together as if he were shutting a book. Sometimes he will accompany this with the word "dat" which is his most common word for book. The next most common words for it are "dot" and "dook."
He also signs for food now by opening his mouth and then putting his hand over it. Very handy one, that. He sometimes also combines the sign with the word "mum."
"Shluck" is his word for sock.
"Car" is now used for pictures or actual cars.
Of course he already had "Kal" and "mum." Any words he has can get used for other things. For instance, the other day he named my nipples. One was called "mum" and the other was called "Kal."
Other times he just says the words because he likes the feel of the word in his mouth, something I also do. But all the words mentioned have a pretty consistent use associated with their respective objects and lifeforms. I tend to wait until I've seen an ongoing use and connection before I credit him with actually understanding the word.
Today, for the first time, he said "da" as he pointed at me. Will be looking out to see if that's repeated or it was a one off.