I once had a professor who always said "Repetition is the branding iron of knowledge". This always made me think of us students as cattle, and our professors as ranchers, searing their most important lessons to our skin. I don't use that quote with the families I work with, but I do teach this principal all the time. When children are having a hard time learning to say words, one of the critical things parents and caregivers can do is frequently repeat the important words in that child's environment in a natural way, and without putting pressure on the child to say the word.
When my daughter was just over a year old, she wasn't yet walking and would frequently pull at the bottom of our pants and lift her arms up to get us to pick her up. We decided 'up' was an important word for her to learn to say, so whenever she tried to get us to pick her up using her non-verbal communication (pulling on our pant legs and lifting her arms up) we would say "oh up, you want to come up"while reaching down to pick her up. Eventually, with enough repetition and emphasizing, she started to crawl to our feet and say "uh, uh" which eventually became "up, up." We didn't cause frustration in her by not giving her what she wanted, but just took the opportunity to model the word she needed over and over again. Pick a word and give this strategy a try.