Select the one-word substitute for the following description: A solemn promise or undertaking.

Introduction / Context:

One-word substitution questions ask you to replace a longer phrase or definition with a concise term that carries the same meaning. In formal and legal contexts, words that describe promises and commitments are very important. The definition here focuses on a solemn promise or undertaking, which implies seriousness, responsibility, and often public or formal declaration.

Given Data / Assumptions:

- The description given is: A solemn promise or undertaking.

- The options are Pledge, Deceit, Myth, and Perjury.

- The word we choose should reflect seriousness and commitment.

- We assume normal English usage without any very specialised religious or legal meanings beyond standard ones.

Concept / Approach:

Pledge means a serious promise or agreement to do something or not to do something. It often involves a sense of honour or obligation. Deceit refers to dishonest behaviour intended to mislead. Myth is a traditional story or widely held but false belief. Perjury is the crime of telling a lie in a court after promising to tell the truth. Among these, only Pledge captures the neutral, formal idea of a solemn promise or undertaking without necessarily involving a courtroom or falsehood.

Step-by-Step Solution:

Verification / Alternative check:

Test each option in sentences similar to the definition. For example, He took a pledge to serve his country faithfully aligns perfectly with the idea of a solemn promise. If we use Deceit, the sentence He took a deceit makes no sense. Replacing it with Myth or Perjury also does not work. Additionally, dictionary entries confirm that pledge is a formal promise or agreement to do something, which is exactly what the question describes.

Why Other Options Are Wrong:

Deceit is wrong because it emphasises dishonesty and trickery rather than commitment. Myth is wrong because it denotes stories or beliefs, not promises. Perjury is wrong because it refers to breaking a sworn promise in a legal setting by lying, which is almost the opposite of fulfilling a solemn undertaking. None of these alternatives captures the neutral and serious sense of a promise conveyed by the definition.

Common Pitfalls:

Some learners confuse legal terms and may pick Perjury because it involves oaths and promises in court, but that word focuses on the violation of an oath, not the oath itself. Others may be attracted to unusual words like Myth without checking if the meaning matches. The best strategy is to focus on the core words in the definition and mentally match them to a simple, known term that you have seen used in similar contexts.

Final Answer:

The correct one-word substitute for a solemn promise or undertaking is Pledge.