Final answer:
A toddler's utterance of 'baba' representing complex ideas such as wanting their bottle or being hungry is known as a holophrase.
Step-by-step explanation:
When a toddler utters "baba," they might be using a holophrase, which is a single word that expresses a complete thought. This term applies to the early stages of child language development, when children know a number of words, but they produce only one-word utterances. The examples you provided, such as "I want my bottle," "Where is my bottle?" or "I'm hungry," can all be communicated with a single word or sound like "baba," demonstrating the communication of complex ideas with a minimal expression.