Final answer:
A child's initial vocabulary predominantly consists of nouns, which are words that refer to familiar objects or events. This noun-focused stage occurs when children are in their early years, particularly between 1 to 2 years old, and continues to be a significant part of their vocabulary as they grow.
Step-by-step explanation:
For the first couple of years, a child's vocabulary is mainly made of nouns. During the early stages of language development, typically between the ages of 1 and 2, children are in the "one-word" stage, where they may know a variety of words but can produce mainly single-word utterances. These words are often nouns that refer to familiar objects or events. For example, a child saying "cookie" could be either identifying a cookie or expressing the desire to have one.
As children reach about 2 years of age, they experience a rapid growth in vocabulary, which continues to expand through the toddler years. By the age of three, children can run, climb steps, and begin to put words together in simple sentences, frequently using nouns they have learned, among other parts of speech. By the age of five, children's vocabulary broadens substantially, including various parts of speech with nouns still constituting a significant part of their spoken and recognized words.