Terms starting with R

19 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.

RAG (Retrieval-Augmented Generation)
Retrieval & generation
A system pattern that retrieves evidence relevant to a request and supplies selected content to a generative model before it answers or acts. Retrieval can use lexical, vector, structured, or hybrid methods.
RLHF (Reinforcement Learning from Human Feedback)
Math & training
A family of pipelines that uses human feedback to learn a reward or preference signal and then optimizes a model policy against that signal. Implementations vary and need not all use the same reinforcement-learning algorithm.
ROUGE
Evaluation & safety
A family of metrics that compares generated text with reference text using units such as n-gram overlap or longest common subsequence.
Rate Limit
AI-native development
A policy that caps requests, tokens, concurrent work, or another resource within a defined time or capacity window.
ReAct
Agents & tools
An agent pattern that interleaves task reasoning, a concrete action, and an observation returned by the environment before deciding the next step.
ReLU
Math & training
Rectified Linear Unit, defined as `f(x) = max(0, x)`. It is inexpensive and has a non-saturating positive branch, though zero gradients on negative inputs can create inactive units.
Readiness Probe
Reliability & operations
A diagnostic that tells the traffic-routing layer whether a service instance is currently able to accept requests.
Recall@K
Retrieval & generation
For one query, Recall@K is `|relevant items intersecting the top k| / |relevant items|`. A dataset score aggregates those per-query values under a stated rule.
Reciprocal Rank Fusion (RRF)
Retrieval & generation
A rank-fusion method that combines several result lists by summing contributions that decrease with each item's rank in each list.
Red Teaming
Security & governance
A structured adversarial testing process in which authorized testers seek failures using documented objectives, threat assumptions, cases, and evidence.
Regression Test
AI-native development
A repeatable check that protects behavior known to work, especially after code, prompt, model, retrieval, or tool changes.
Repository Instructions
AI-native development
Version-controlled guidance that tells coding agents how a repository is organized, which commands and conventions apply, what boundaries to respect, and how to verify work.
Repository Map
AI-native development
A compact, maintained description of a repository's important directories, ownership boundaries, entry points, build commands, tests, generated files, and local instructions.
Reproducible Build
AI-native development
A build whose declared source, environment, and instructions can be independently rerun to produce bit-for-bit identical specified artifacts.
Reranker
Retrieval & generation
A second-stage model or scoring function that reorders a small candidate set using a richer comparison between the query and each candidate.
Retry Budget
Reliability & operations
A bound on retry traffic, usually expressed relative to original requests or over a time window, that prevents retries from consuming unbounded capacity.
Retry with Backoff
AI-native development
Repeating a failed transient operation after progressively longer delays, usually with randomized jitter and a strict retry limit.
Reviewer Agent
AI-native development
An agent assigned to inspect another agent's artifact or decision against explicit criteria and return findings or a verdict.
Rollback
Reliability & operations
Restoring a previously known deployment or configuration when the current release violates operational, quality, or safety criteria.