In the following question on idioms, choose the alternative that best expresses the meaning of the word "Catnap".

Introduction / Context:
English contains many informal terms for different types of sleep. One such term is catnap, which appears in magazines, conversation, and even health advice columns. Understanding these words helps readers interpret descriptions of daily routines and lifestyles more accurately. This question asks for the best explanation of the term catnap among the options given.

Given Data / Assumptions:
The word provided is catnap. The options describe different kinds of rest and sleep, including rest, fitful sleep, long sleep, short sleep, and another variation. We assume that the test taker has encountered the everyday expression take a catnap, which usually refers to a brief period of sleep taken during the day to refresh oneself.

Concept / Approach:
A catnap is a very short, light sleep, often taken while sitting or lying down for a limited time, such as ten or twenty minutes. It is not a full night’s sleep and not necessarily disturbed or restless. The image compares a person’s sleep to the way a cat dozes lightly, waking up quickly. Therefore, the option that best captures this sense is short sleep. While fitful sleep involves repeated waking and unrest, it does not have to be short. Rest is broader and may not include actual sleep. Long sleep is clearly the opposite of what the word suggests.

Step-by-Step Solution:
Step 1: Recall the common phrase take a catnap meaning to sleep briefly.
Step 2: Note that a catnap emphasises short duration rather than depth or quality of sleep.
Step 3: Compare this idea with each option and check which one highlights briefness.
Step 4: Identify short sleep as the choice that clearly captures duration and matches usage.
Step 5: Select short sleep as the correct meaning of catnap.

Verification / Alternative check:
Example sentences support this meaning: After lunch he took a quick catnap in his chair, or She relies on short catnaps during long flights. In each sentence, catnap refers to a brief period of sleep, often used as a power nap. None of these examples indicate a long sleep or restless tossing and turning. This context based check confirms that the option short sleep matches conventional use.

Why Other Options Are Wrong:
Option A, rest, can mean relaxation without sleep, so it is too general and does not reflect the specific idea of actual sleep. Option B, fitful sleep, emphasises disturbed quality, not length, and may last for hours. Option C, long sleep, is the direct opposite of the short nap that catnap signifies. Option E, sleep with dreams, adds an element that is not part of the idiom's meaning and could apply to any sleep. Therefore, only short sleep fits both everyday usage and the imagery behind the term catnap.

Common Pitfalls:
Students may confuse catnap with general rest or think the word suggests broken or uneasy sleep because of the image of alert cats. It is important to focus on the feature that dictionaries and common usage highlight: the brief duration. Learning groups of related terms like nap, doze, snooze, and slumber, along with their typical contexts, helps build a more precise vocabulary and avoid mistakes in such questions.

Final Answer:
The word catnap means short sleep.