Which word describes a style of speaking or writing that is concise and clear?

The term that best describes a style of speaking or writing that is concise and clear is succinct. When language is succinct, it conveys information effectively without unnecessary words or embellishments, making it easier for the audience to understand the message. This quality is valuable in both speaking and writing as it helps to maintain the listener's or reader's attention and ensures that the key points are communicated efficiently.

In contrast, verbose refers to language that is overly wordy or uses more words than needed, which can lead to confusion or boredom in the audience. Grandiloquent describes a style that is pompous or extravagant, often employing lofty language that can obscure meaning instead of clarifying it. Ambiguous signifies a lack of clarity, where the meaning of the words may be unclear or open to multiple interpretations, which is the opposite of being clear. Thus, succinct is the most appropriate choice in this context.