What is the meaning of Singleton_pattern?

5-letter words containing

• 5-letter words containing y

• 5-letter words containing u

• 5-letter words containing p

• 5-letter words containing e

• 5-letter words containing u

5-letter words starting with

• 5-letter words starting with e

• 5-letter words starting with g

• 5-letter words starting with u

• 5-letter words starting with y

• 5-letter words starting with a

5-letter words in the middle

• 5-letter words in the middle i

• 5-letter words in the middle e

• 5-letter words in the middle c

• 5-letter words in the middle d

• 5-letter words in the middle e

5-letter words ending with

• 5-letter words ending with w

• 5-letter words ending with t

• 5-letter words ending with k

• 5-letter words ending with o

• 5-letter words ending with a

5-letter words excluding

• 5-letter words excluding n

• 5-letter words excluding f

• 5-letter words excluding o

• 5-letter words excluding i

• 5-letter words excluding i