Final answer:
Toddlers experience significant lexical variability in their language development, with their vocabulary expanding from one- and two-syllable words to using sentences and asking questions by 2-3 years old. By 4-5 years old, children have a larger vocabulary, can define words, and speak fluently with slang and clichés.
Step-by-step explanation:
Toddlers experience significant lexical variability as they develop language skills. At 1-2 years old, toddlers use one- and two-syllable words and understand several other words. By 2-3 years old, their vocabulary expands to include up to 1,000 words, and they can speak in sentences and ask questions. By 4-5 years old, children have a vocabulary of about 6,000 words and can define words and question their meanings. They can also speak fluently and use slang and clichés.