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Digital dictionary

The dictionary  defines frequently used terms, processes and technologies used in digital engineering.



A series of steps that a computer program works through to produce an output. Sometimes used interchangeably with model ‘code’, but this may be misleading as a model often contains several algorithms.


The process of ensuring a product meets its intended requirements and legal obligations.

Application lifecycle management (ALM)

ALM is the lifecycle management of software applications, which includes governance, development, and maintenance.

Application Programming Interface (API)

API is a computing interface that defines interactions between multiple software or mixed hardware-software intermediaries.

Artificial Intelligence (AI)

AI enables computers and machines to mimic the perception, learning, problem-solving, and decision-making capabilities of the human mind.

Augmented Intelligence

A conceptualisation of artificial intelligence that focuses on AI's assistive role, emphasizing the fact that cognitive technology is designed to enhance human intelligence rather than replace it.



Central Processing Unit (CPU), Graphics Processing Unit (GPU), Quantum Processing Unit (QPU)

The computer's CPU is a specialised electronic circuit designed to retrieve and executes instructions. It is the primary component of a computer that processes instructions.

A GPU is a specialised electronic circuit designed to rapidly manipulate and alter memory to accelerate the creation of images in a frame buffer intended for output to a display device.

A QPU is a computational unit that uses quantum computing principles to perform a processing task.


This is a process or action to ensure the actual functionality of a product, service, or system does achieve its specific regulatory requirements.

Computing Architectures



A mechanism to reduce the reliance on fossil-based energy stores.

Design Space

The design space is the multidimensional region defined by the input variables and process parameters.

Device Attestation

Device Attestation is a mechanism which allows organisations to learn about the security stance of devices that are trying to connect to enterprise applications and workspaces by making a claim about the properties of a target, providing cryptographically signed evidence about the state of the device .

Digital Thread

Digital Thread is a framework which connects data flows and produces a holistic view of an asset's data across its product lifecycle. This framework addresses protocols, security, and standards. The digital thread connects digital twins, digital models of physical assets, or groups of assets.

Digital Twin

A computational model of physical assets (or processes or systems) that continuously learns and updates itself from multiple sources, as the physical counterparts change. It acts as a bridge between the physical and virtual world, allowing analysis (e.g. simulations) that can help to anticipate problems and plan for the future.

Distributed Ledger

A distributed ledger is a digital database that is consensually shared and synchronised across multiple sites, institutions, or geographies, accessible by multiple people. Any changes or additions made to the ledger are reflected and copied to all parties in a matter of seconds or minutes. An example of Distributed Ledger Technology is Blockchain.


Edge Computing

Edge computing is a distributed computing method shift that brings computation and data storage closer to the location where it is needed, to improve response times and save bandwidth. Essentially computing is carried out at or near the source of the data, to improve response times and save bandwidth.


The action of estimating or concluding something by assuming that existing trends will continue, or a current method will remain applicable beyond the original observation range.



Fidelity is the measure of how close to reality a model or simulation is.

Fog Computing

This is an architecture that uses and orchestrates Edge Computing devices to carry out a substantial amount of computation, storage, and communication locally and routed over the Internet backbone/cloud.



Hardware-in-the-Loop (HiL)

HIL is a technique that is used in the development and test of complex real-time embedded systems, where real signals from a controller are connected to a test system that simulates reality, tricking the controller into thinking it is in the assembled product.

High Performance Computing (HPC)

HPC is the ability to process data and perform complex calculations at high speeds aggregating multiple processing units.

Homomorphic Encryption

Homomorphic Encryption enables calculations on encrypted data without decrypting it first. The result of the computation is in an encrypted form and when decrypted, the output is the same as if the operations had been performed on the unencrypted data.






Machine Learning

Machine learning is a branch of AI that enables systems to learn and improve automatically through experience.


Model Based Design

A mathematical and visual method of solving design problems, characterised by defined continuous systems and/or discrete event models of functional characteristics.

Model Based Environment

A common environment, which facilitates the approach of Model Based Systems Engineering to ease communication, data analysis, system verification and testing across the product and service lifecycle.

Model Based Systems Engineering (MBSE)

MBSE is the approach of developing a set of related system models that help define, design, test and validate system characteristics earlier, in a cost-effective way to explore and document whole system characteristics. This systems modelling helps facilitate timely learning of properties and behaviours, enabling fast feedback on requirements and design decisions.


This is the process of creating a representative approximation of a real-world object, feature or condition. These can be either physical or mathematical or the logical representation of a system, entity, phenomenon, or process.

Model-in-the-loop (MiL) testing

Model-in-the-loop testing (MIL) is a technique used to abstract the behaviour of a system so that the model can be used to test, simulate and verify itself.


A broad spectrum use of different fidelity of data or models in simulations.


The modelling and simulation of multiple material flows with two or more thermodynamic phases.


The modelling and simulation of multiple natural physical phenomenon interactions concurrently on real world-objects, features or conditions.


Multiscale modelling refers to a style of modelling in which multiple models at different scales of time and space are used simultaneously to describe a system.




Ontology is a formal framework that describes concepts within a system based on relationship between domains (established through their definitions, and which avoids overlaps and ambiguities) using constraints.


Platform as a Service (PaaS)

PaaS is a complete development and deployment environment in the cloud, with resources that enable to deliver everything from simple cloud-based apps to sophisticated, cloud-enabled enterprise applications


Quantum Computing

Quantum computing is the use of quantum phenomena such as superposition and entanglement to perform computation. Computers that perform quantum computations are known as quantum computers.




This is the process of analysing a representative approximation (the model) of a real-world object, feature or condition.

Software as a Service (SaaS)

SaaS is a method of software delivery and licensing in which software is centrally hosted and accessed online via a subscription.

Software-in-the-loop (SiL)

SiL is a test methodology where executable code such as algorithms, usually written for a particular mechatronic system, is tested within a modelling environment that can help prove or test the software.


A self-contained system within a larger system. For example, within a vehicle, a powertrain would be a sub-system, the vehicle a system and the wider interactions of that vehicle with infrastructure would be super system.

Super System

A system that is made up of multiple other systems. For example, within a vehicle, a powertrain would be a sub-system, the vehicle a system and the wider interactions of that vehicle with infrastructure would be super system.

Synthetic Data

Synthetic data is data that is artificially created rather than being generated by physical events.


A system is a group of interacting or interrelated entities that form a unified whole. For example, within a vehicle, a powertrain would be a sub-system, the vehicle a system and the wider interactions of that vehicle with infrastructure would be super system.



Tactility is the measure of throughput and capacity of networks, including latency, reliability, and connection density, while still meeting requirements for security, trust, identity and privacy.


Taxonomy is the process of assigning an object to a specific domain based on their definition.


Uncertainty quantification

The science of measuring and reducing unknowns in both computational and real-world applications. This tries to determine how 'likely' and probable event outcomes are when some aspects of a system are unknown.

User Experience (UX or UE)

UX or UE is about how a user interacts but also experiences, a particular product, system or service. It includes a person's perceptions of utility, ease of use, and efficiency.

User Interface

The means by which a user and a computer system can interact. This covers the varied use of input devices within software tools.



The assurance that a product, service, or system meets the needs of the customer and other identified stakeholders. It often involves acceptance and suitability with external customers.


The evaluation of whether or not a product, service, or system complies with a regulation, requirement, specification, or imposed condition. It is often an internal process.

Virtual Machine (VM)

A virtual machine is the emulation of a computer system by using software instead of physical compute to run programs and deploy other S/W applications.

Visualisation System

A visual representation of information or data.


X-in-the-Loop (XiL)

XiL is an integrated in-loop method where X refers to the unit under test, which can be a model (model in the loop, MiL), software (software in the loop, SiL), and hardware (hardware in the loop, HiL).



We welcome suggestions for additional terms suitable for inclusion in the dictionary, as well as feedback on terms and definitions that could be improved.


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