# Glossary > Plain definitions of the words this site uses about leads, handoffs and the systems between your tools, written for owners of service businesses. This glossary gives plain definitions of the words I use on this site about leads, handoffs and systems, written for owners. Each term opens with a one-sentence definition, then says why it matters to a service business, walks through an example, and describes how a system handles it, in the words you'd use yourself. The same few words come up every time I talk with an owner about a lead that went cold or a contact that turned up twice. When we both mean the same thing by speed to lead or a bottleneck, it's quicker to see where your own business is stuck and what would move it. - [Bottleneck](https://signalnine.io/glossary/bottleneck): A bottleneck is the one stage that limits how much your whole business can move. The Theory of Constraints in plain words, with an example and the fix. - [Closed-won to kickoff](https://signalnine.io/glossary/closed-won-to-kickoff): Closed-won to kickoff is the gap between a client signing and the project starting. What has to happen in it, where it breaks, and how a system runs it. - [CRM hygiene](https://signalnine.io/glossary/crm-hygiene): CRM hygiene is keeping CRM records accurate, complete and free of duplicates. Why it decays, what it breaks, and how a system keeps it as a routine. - [Dedupe key](https://signalnine.io/glossary/dedupe-key): A dedupe key is the field a system uses to decide two records are the same person or company. Which key to pick, an example, and what goes wrong without one. - [Handoff](https://signalnine.io/glossary/handoff): A handoff is the moment work passes from one person, team or tool to the next. Why work waits and details get lost there, and how a system carries them. - [Human-in-the-loop approval](https://signalnine.io/glossary/human-in-the-loop-approval): What human-in-the-loop approval means in an automation, which steps should wait for a person, and how an approval card makes sure an email sends once. - [Lead reactivation](https://signalnine.io/glossary/lead-reactivation): Lead reactivation means going back to leads and past clients that went cold, with a reason to talk now. Why it matters and how a system keeps it running. - [Pipeline stall](https://signalnine.io/glossary/pipeline-stall): A pipeline stall is a deal that has stopped moving but still counts in the forecast. How to spot a stalled deal and how a system flags it in time. - [Retainer re-setup](https://signalnine.io/glossary/retainer-re-setup): Retainer re-setup is rebuilding the same project every month for each retainer client. Why it costs margin and how a system sets up each month from a template. - [Scope creep](https://signalnine.io/glossary/scope-creep): Scope creep is work a client gets that was never agreed, added one small request at a time. How the invisible kind eats agency margin and how to see it. - [Send-once](https://signalnine.io/glossary/send-once): Send-once means one approval sends one email, however many times the button gets pressed. Why duplicates happen and how a system keeps the rule. - [Source of truth](https://signalnine.io/glossary/source-of-truth): The one system whose copy of a record wins when two tools disagree. Why it matters for opt-outs and phone numbers, and how a one-way sync keeps it that way. - [Speed to lead](https://signalnine.io/glossary/speed-to-lead): Speed to lead is the time between a lead reaching you and a real reply going back. Why it matters, an example, and how a system shortens it. - [Stock and flow](https://signalnine.io/glossary/stock-and-flow): Stock and flow sees a pipeline as a pile of open deals and the rates at which deals enter and leave. Why the rates matter more than the pile. - [Webhook](https://signalnine.io/glossary/webhook): A webhook is a message one app sends another the moment something happens. What that means in plain English, how it fails, and how a system catches it. [BOOK A FREE CONSULTATION](https://cal.com/mashrur-signalnine/30min) ## Related - [Integrations](https://signalnine.io/integrations): Handoffs between two tools, judged the way an owner would: where each one breaks, which system holds the truth, how duplicates are stopped, what stays human. - [Comparisons](https://signalnine.io/compare): Decision pages for owners: a criteria table, where each option falls short, and a pick for each situation. --- Mashrur Rahman, Founder, SignalNine. Published 2026-10-04, updated 2026-10-04. Canonical: https://signalnine.io/glossary