What is the meaning of Non-restrictive_relative_clause?

5-letter words containing

• 5-letter words containing s

• 5-letter words containing i

• 5-letter words containing t

• 5-letter words containing l

• 5-letter words containing e

5-letter words starting with

• 5-letter words starting with a

• 5-letter words starting with u

• 5-letter words starting with g

• 5-letter words starting with e

• 5-letter words starting with w

5-letter words in the middle

• 5-letter words in the middle a

• 5-letter words in the middle i

• 5-letter words in the middle k

• 5-letter words in the middle i

• 5-letter words in the middle p

5-letter words ending with

• 5-letter words ending with l

• 5-letter words ending with a

• 5-letter words ending with v

• 5-letter words ending with r

• 5-letter words ending with e

5-letter words excluding

• 5-letter words excluding y

• 5-letter words excluding s

• 5-letter words excluding t

• 5-letter words excluding d

• 5-letter words excluding i