Understanding One-Word Substitution for Unprepared Speeches

The question asks for a single word that means "A speech delivered without preparation". This is a common vocabulary exercise testing knowledge of specific terms related to speaking.

Analyzing the Options for Unprepared Speech

Let's look at each option to find the correct substitution:

• Soliloquy: This term refers to a speech where a character speaks their thoughts aloud, often when they are alone on stage. It's about expressing inner thoughts, not necessarily about being unprepared. For example, Hamlet's famous "To be or not to be" speech is a soliloquy.
• Rebuttal: A rebuttal is a response given to contradict or argue against something that has been said. It's a form of counter-argument, not a speech given without prior thought. Think of a debate where one side presents a rebuttal to the other's points.
• Monologue: A monologue is a lengthy speech delivered by one person, often part of a dramatic work. While it can sometimes be delivered with little specific preparation (like an actor improvising a longer speech), the core meaning is just a long speech by one person, not specifically one given *without preparation*.
• Impromptu: This word perfectly describes something done without being organised or planned in advance. An impromptu speech is exactly that – a speech delivered with little or no preparation. It is spontaneous.

Identifying the Correct Substitution

Based on the definitions, the term that specifically means "A speech delivered without preparation" is Impromptu.

Therefore, the correct one-word substitution is Impromptu.