How can I represent a list of words and related words in a relational structure? I have a list of header words and words as below and I am trying to understand how best to represent these in a relational table:

Header      Other
Words       Words

abandon     abandoned, abandoning, abandonment, abandons
abstract    abstraction, abstractions, abstractly, abstracts
access      accessed, accesses, accessibility, accessible, accessing, inaccessible  access
accommodate accommodated, accommodates, accommodating, accommodation    accommodate
accompany   accompanied, accompanies, accompaniment, accompanying, unaccompanied    accompany
accumulate  accumulated, accumulating, accumulation, accumulates


The problem is that for every word I have additional information such as pronunciation. 

What I am thinking of is two tables:

CREATE TABLE [dbo].[Word] (
    [WordId]         INT           IDENTITY (1, 1) NOT NULL,
    [Word]           NVARCHAR(50)  NOT NULL,
    [Pronounciation] NVARCHAR(100) NULL,
    [Other columns follow ...
)

CREATE TABLE [dbo].[WordRelationship] (
    [WordRelationshipId]  INT IDENTITY (1, 1) NOT NULL,
    [HeaderWordId]        INT NOT NULL,
    [OtherWordId]         INT NOT NULL,
)


I would like to get some suggestions from the members here
That is pretty much how you have to do it. The relationship table for a many-to-many link like that is often called a junction table (though goes by many other names on occasion: map table, mapping table, bridge table, ...).

If you have more than one class of relationship between words (abbreviation, antonym, synonim, ..) than that should be in the junction table too.

If you don't have multiple relationship types then there may be no need to have WordRelationshipId: the most efficient way to store what you currently have in SQL Server is just HeaderWordId, WordID with the two columns together being the primary key and that key being clustered (though as a matter of style/consistency some people prefer to have a separate surrogate key for all entities, and some frameworks baulk at composite PKs, so YMMV).