Engineering Glossary

This glossary defines the foundational engineering terminology used throughout the Engineering Knowledge Framework.

Purpose

This glossary defines the foundational engineering terminology used throughout the Engineering Knowledge Framework.

Every term defined here is authoritative across the entire repository.

Capability-specific terminology belongs in the corresponding capability glossary (e.g., Architecture Glossary, Rails Glossary).

Property	Value
Definition	The process of hiding implementation details behind a
	simplified interface, exposing only essential
	characteristics.
Context	Abstraction reduces complexity by allowing engineers to
	work at a higher level of understanding. It is a
	fundamental tool for managing software complexity.
Related	Encapsulation, Modularity
References	Engineering Fundamentals Handbook

Property	Value
Definition	The degree to which elements within a module belong
	together and serve a single, well-defined purpose.
Context	High cohesion indicates that a module's responsibilities
	are closely related and focused. Low cohesion means a
	module attempts to do many unrelated things. High
	cohesion is preferred.
Related	Coupling, Separation of Concerns
References	Engineering Fundamentals Handbook

Property	Value
Definition	A design principle in which complex behaviour is built
	by combining small, focused, reusable components rather
	than inheriting behaviour from a parent class.
Context	Composition is preferred over inheritance in most
	cases because it is more flexible, easier to test and
	less likely to produce fragile code.
Related	Coupling, Encapsulation
References	Engineering Fundamentals Handbook

Property	Value
Definition	The degree of dependency between two modules or
	components.
Context	Loose coupling means modules interact through stable,
	minimal interfaces and can be changed independently.
	Tight coupling means changes to one module require
	changes to others. Loose coupling is preferred.
Related	Cohesion, Encapsulation
References	Engineering Fundamentals Handbook

Property	Value
Definition	A technique in which an object receives its dependencies
	from an external source rather than creating them
	internally.
Context	Dependency injection makes dependencies explicit,
	simplifies testing and reduces coupling. Common forms
	include constructor injection, setter injection and
	interface injection.
Related	Coupling, Encapsulation
References	Engineering Fundamentals Handbook

Property	Value
Definition	The practice of hiding internal implementation details
	behind a stable interface, protecting internal
	invariants from external interference.
Context	Encapsulation enables change by ensuring that internal
	refactoring does not affect consumers. A well-
	encapsulated component exposes only what is necessary.
Related	Abstraction, Modularity
References	Engineering Fundamentals Handbook

Property	Value
Definition	The degree to which a system is composed of discrete,
	independent modules that can be developed, tested and
	changed in isolation.
Context	Modularity is a key tool for managing complexity. It
	enables parallel development, simplifies testing and
	reduces the impact of changes.
Related	Cohesion, Coupling, Encapsulation
References	Engineering Fundamentals Handbook

Property	Value
Definition	The disciplined practice of improving code structure
	without changing its observable behaviour.
Context	Refactoring is an ongoing activity, not a separate
	project. It should be driven by clear goals, supported
	by tests and done incrementally.
Related	Technical Debt
References	Engineering Fundamentals Handbook

Property	Value
Definition	A design principle stating that each module, class,
	function or component should have a single, clearly
	defined responsibility.
Context	Separation of concerns is the foundation of modular
	design. It reduces complexity, improves maintainability
	and enables independent evolution of different parts
	of a system.
Related	Cohesion, Coupling, Modularity
References	Engineering Fundamentals Handbook

Property	Value
Definition	The gap between the current state of a codebase and the
	desired state, representing future work required to
	address suboptimal design, implementation or testing
	decisions.
Context	Technical debt may be strategic (intentional with a
	plan to repay) or accidental (accumulated through
	neglect). All technical debt should be tracked
	explicitly and regularly addressed.
Related	Refactoring
References	Engineering Fundamentals Handbook