Terms starting with A

22 of 250 glossary terms. Each entry links to its own page with why it matters and where it fits.

Definitions here are written for engineers, not grammarians: what the term means, why it matters when it comes up, and where it sits in the curriculum — most term pages name the lessons that lean on the concept, so you can jump from a definition straight to the teaching. Use the letter bar below to move through the alphabet, or press the slash key to search the whole corpus directly.

Every entry carries three things besides the definition: the plain aliases it travels under (listed as “also”), a category tag for which stretch of the curriculum it belongs to, and the cross-references that place it next to its neighbors — the terms you would meet in the same lesson. A term earns a page here only when a lesson in the curriculum actually uses it, so the corpus stays the shape of the material instead of the shape of a dictionary.

One honest way to use this page: read down the list of entries below and note every term you could not define in a sentence if a colleague asked. That list — not the whole letter — is your revision list, and each entry links to the reading that closes the gap.

AI Risk Assessment
Security & governance
A documented analysis of how an AI system can affect people, organizations, and environments, including context, hazards, likelihood, impact, controls, residual risk, and monitoring responsibilities.
Activation Checkpointing
Math & training
A training-memory technique that saves only selected forward-pass activations and recomputes the omitted ones during backpropagation.
Activation Function
Math & training
A function applied after a linear or affine layer that introduces nonlinearity. Without it, composing layers with weights and biases collapses to one affine transformation. ReLU, GELU, and SiLU are common choices. The choice directly affects whether gradients flow during training.
Adam (Optimizer)
Math & training
Adaptive Moment Estimation. It combines an exponential average of gradients with an exponential average of squared gradients, applies bias correction, and adapts the update scale per parameter. It is a useful baseline, but it still needs a suitable learning rate and schedule.
AdamW
Math & training
An Adam variant that decouples weight decay from the gradient-based parameter update. That makes the shrinkage behavior easier to reason about than adding an L2 penalty inside Adam's adaptively scaled gradient.
Admission Control
Reliability & operations
A pre-acceptance gate that decides whether a request may enter a bounded queue or service under the system's current capacity, priority, and policy.
Agent
Agents & tools
A software system that lets a model select actions toward a goal, observe tool or environment results, and continue under an orchestration policy. An agent may use a loop, a state machine, a workflow engine, or human approvals. The model is one component, not the entire system.
Agent Harness
Agents & tools
The runtime around a model that assembles context, exposes tools, manages state, enforces limits, records traces, and decides when the agent should continue, retry, ask, or stop.
Agent Memory
Agents & tools
Information stored outside the model and selected for use in later agent steps, such as prior decisions, user preferences, task episodes, or verified facts.
Agent Skill
Agents & tools
A discoverable directory of procedural instructions whose entry point is `SKILL.md`, with optional references, scripts, and assets that a compatible runtime can load in stages.
Agent State
Agents & tools
The explicit data an agent carries across steps, such as the current objective, completed actions, tool results, open questions, budgets, approvals, and artifact references.
Alignment
Evaluation & safety
The effort to make a model or AI system behave in ways that match intended goals, constraints, and human preferences across both expected and adversarial situations.
Approval Gate
Agents & tools
A control point that blocks a consequential action until an authorized person or policy grants permission.
Approximate Nearest Neighbor (ANN)
Retrieval & generation
A search method that returns vectors likely to be among the nearest to a query without exhaustively comparing the query with every stored vector.
Attention
Models & inference
A mechanism that forms contextual representations by comparing query vectors with key vectors, normalizing the resulting scores, and using them to combine value vectors. Masks, position rules, or sparse patterns can restrict which positions participate.
Audio Token
Multimodal systems
A discrete identifier produced by an audio codec or tokenizer for a short segment or feature of an audio signal, sometimes across several codebooks.
Audit Log
Security & governance
A durable, access-controlled record of security- or accountability-relevant events, including who or what acted, what changed, when it happened, and the resulting status.
Autograd
Math & training
A system that records or transforms tensor operations so it can compute derivatives, usually with reverse-mode automatic differentiation. You write the forward computation and the framework derives the gradients needed for backpropagation.
Automatic Speech Recognition (ASR)
Multimodal systems
The task and system pipeline that maps a speech signal to a transcription, often with optional token or segment timing and confidence information.
Autoregressive
Models & inference
A factorization in which each output token is predicted from the tokens that precede it. During generation, the selected token is appended to the sequence and becomes part of the next prediction's context.
Autoscaling
Infrastructure & serving
A control loop that changes the number or capacity of serving workers from observed demand, resource use, or application metrics within configured bounds.
Availability
Reliability & operations
The proportion of eligible service interactions or time windows in which users can obtain the defined acceptable service under a stated measurement boundary.