The first word Helen understands and appropriately uses is water.
In working with Annie, Helen has begun to learn various letters and has even begun to spell some of her favorite objects, like cake. Yet Annie realizes that Helen has failed to realize that the series of letters she replicates from Annie's instruction actually convey the meanings of objects. Instead, she simply repeats what Annie does to get things that she desires.
Everything changes one day at the water pump. This time, as the water tumbles over Helen's hand and Annie spells water into her free palm, Helen's face shows the evidence of recognition. She stands "transfixed" as she tries to remember the language she had last used as a toddler. Helen's mouth forms the sounds of "wah wah" in response to the water. Annie encourages her, and Helen spells the word water into Annie's hand.
Finally recognizing the significance of all those taps into her palm, Helen grabs for more water, plunging her hand into it again and then offering her palm for Annie to spell the word again for her. She then drops to the ground, patting it and then offering her palm for Annie to spell this word as well.
It is the word water, often symbolic of life and change, that transforms Helen's world. When she connects the feeling of water to Annie's instruction, Helen's first word changes her entire existence.