What is the umbrella sentence of a paragraph called?

The umbrella sentence of a paragraph is typically called the topic sentence.

Here's why:

* It sets the overall topic: Like an umbrella, the topic sentence covers the entire scope of the paragraph's content.

* It guides the reader: The topic sentence provides a clear indication of what the paragraph will be about, helping the reader understand the main point.

* It summarizes the main idea: The topic sentence encapsulates the essence of the paragraph, making it easily digestible.

While some might refer to it as the "main idea" or "controlling idea" sentence, "topic sentence" is the most widely accepted term.