In English vocabulary, select the synonym (similar meaning word) of the noun "crown" when it is used in the sense of the top or highest point of something.

Introduction / Context:
This English vocabulary question tests your understanding of synonyms, which are words that have similar meanings. Specifically, it asks for a synonym of the noun "crown" when the word is used in the sense of the top or highest point of something, such as the crown of a hill or the crown of a tree. Understanding such figurative meanings helps in reading comprehension, descriptive writing, and competitive exam questions that focus on nuanced word usage.

Given Data / Assumptions:

• The word in focus is the noun "crown".
• The sense required is the top or highest point, not the object worn by a king.
• Five options are provided: apex, frown, nadir, base, rim.
• Exactly one option must express a similar meaning to "crown" in the given sense.

Concept / Approach:
The key idea is that many English words have multiple meanings, and the correct synonym depends on the context. "Crown" can mean a metal headpiece worn by royalty, but it also commonly refers to the highest part of something, like the crown of a mountain. To solve synonym questions, first identify which sense of the word fits the definition implied by the question. Then, compare that meaning with each option and eliminate words that are unrelated or opposite in meaning.

Step-by-Step Solution:
Step 1: Recognise that the question uses "crown" in the sense of the highest point or top, not a royal ornament. Step 2: Recall that "apex" means the top or highest part of something, especially one forming a point, which matches this sense of "crown". Step 3: Note that "frown" refers to a facial expression showing displeasure, which is unrelated to physical height or position. Step 4: Understand that "nadir" means the lowest point, which is actually the opposite of "crown" in this context. Step 5: See that "base" is the bottom or lowest part of something, again opposite in meaning to a highest point. Step 6: The word "rim" refers to an edge or border, which may sometimes be high, but does not specifically mean the topmost point. Step 7: Therefore, "apex" is the only option that correctly captures the meaning of "crown" as the top or highest point.

Verification / Alternative check:
You can verify your choice by substituting each option into an example sentence. For instance, in the sentence "We reached the crown of the mountain," replacing "crown" with "apex" gives "We reached the apex of the mountain," which sounds natural and accurate. Replacing it with "base" or "nadir" reverses the meaning, and "frown" simply makes no sense. This substitution method is a quick way to check synonym questions in exams.

Why Other Options Are Wrong:

• frown: Refers to a facial expression of displeasure or worry and has no connection to height or topmost position.
• nadir: Means the lowest point of something, which is the opposite of the highest point implied by "crown".
• base: Refers to the bottom or supporting part of an object, again opposite to a highest point.
• rim: Refers to an outer edge or border, such as the rim of a cup, and does not specifically mean the very top point.

Common Pitfalls:
A common mistake is to think only of "crown" as a royal headpiece and get distracted by options that might emotionally feel similar, even if they are not semantically related. Another pitfall is to confuse "nadir" with "apex" because both are used in discussions of highs and lows. Remember that "apex" is the maximum or top point, whereas "nadir" is the minimum or lowest point. Always focus on the precise meaning required by the question context rather than superficial associations.

Final Answer:
The synonym of "crown" when it is used to mean the top or highest point is apex.