Choose the one word substitute for the expression "the way in which a substance holds together; thickness or viscosity".

Introduction / Context:
This question asks you to replace a descriptive phrase with a single precise English word. The phrase given relates to the physical behaviour of a substance, particularly how thick or viscous it is. Such scientific and everyday terms are useful in academic writing, cooking instructions, and laboratory descriptions.

Given Data / Assumptions:

• The phrase is: "the way in which a substance holds together; thickness or viscosity".
• Options are: corpulency, consistency, exigency, exultancy, rigidity.
• Exactly one option should match the physical idea of how a substance holds together.
• We assume common general science and English vocabulary knowledge.

Concept / Approach:
The description clearly points to a physical property of materials. In everyday English, when we talk about how thick a sauce is or how viscous a liquid is, we often talk about its "consistency". Other options either refer to completely different concepts or have different roots. Identifying Greek or Latin roots can help distinguish between them.

Step-by-Step Solution:
Step 1: Recognise that the phrase refers to how a substance holds together and how thick or thin it is. Step 2: Recall that "consistency" is often used to describe whether a liquid is thick, thin, smooth, or lumpy, such as "a thick consistency". Step 3: Examine "corpulency". This refers to the state of being fat or obese, describing a person, not a physical property of materials. Step 4: Look at "exigency". It means an urgent need or demand and belongs to the field of situations, not physical properties. Step 5: Consider "exultancy". It is related to "exultation" and refers to a feeling of great joy or triumph, unrelated to substances. Step 6: "Rigidity" means stiffness or inflexibility, which is more about solid objects rather than the general thickness of substances like creams or sauces. Step 7: Therefore, "consistency" is the only option that correctly matches the given definition.

Verification / Alternative check:
Think of common expressions: "Check the consistency of the soup" or "The paint has the wrong consistency for this work". In each case, "consistency" describes how the substance holds together and how thick or viscous it is. None of the other options fit sensibly in these sentences, confirming that they do not share this meaning.

Why Other Options Are Wrong:

• corpulency: Refers to physical fatness or stoutness in a person, not to the property of a substance.
• exigency: Means urgent need or demand, usually in legal or emergency contexts.
• exultancy: Linked to feelings of triumph and joy, purely emotional rather than physical.
• rigidity: Describes stiffness or inflexibility, especially in solids or behaviour, not general thickness or viscosity.

Common Pitfalls:
Students may be tempted by words that simply "sound technical" like "exigency" or "rigidity". However, one word substitution questions require precise matching of meaning. Always map each option back to its core definition instead of relying on sound or complexity. Regular exposure to science texts and recipes helps cement the real usage of "consistency".

Final Answer:
The correct one word substitute is consistency.