Have you read the Basics of Scope Management article yet? You might have noticed a quirky equation in the end,
Scope Baseline = Project Scope Statement + Work Breakdown Structure + WBS Dictionary
While all other topics are already covered under the Scope Management knowledge area, now is the time to introduce the WBS.
A basic textbook definition is,
WBS dictionary is the document that provides detailed information about every element of the WBS.
We did talk about the WBS dictionary a bit in this Lounge Fever video. Typically, a WBS Dictionary entry will be made for each WBS element with details like a Work Package details, description or statement of work, acceptance criteria, deliverables, cost, schedule etc.
Work Breakdown Structures include a numbering system (also known as the Code of Accounts) and this numbering system is referred to in the WBS Dictionary to point to the corresponding WBS element making it easier for the stakeholders to read it.
Below is a sample WBS Dictionary entry for System Requirements document,

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In one of the video regarding WBS it was explained that , there should not be dependency among the WBS elements , Here in WBS how we are showing dependency.
Which video are you talking about? Need more context.