What is the meaning of Metasyntactic_variable?

5-letter words containing

• 5-letter words containing c

• 5-letter words containing t

• 5-letter words containing e

• 5-letter words containing s

• 5-letter words containing e

5-letter words starting with

• 5-letter words starting with a

• 5-letter words starting with o

• 5-letter words starting with i

• 5-letter words starting with s

• 5-letter words starting with k

5-letter words in the middle

• 5-letter words in the middle l

• 5-letter words in the middle A

• 5-letter words in the middle r

• 5-letter words in the middle s

• 5-letter words in the middle f

5-letter words ending with

• 5-letter words ending with l

• 5-letter words ending with r

• 5-letter words ending with e

• 5-letter words ending with r

• 5-letter words ending with i

5-letter words excluding

• 5-letter words excluding u

• 5-letter words excluding a

• 5-letter words excluding n

• 5-letter words excluding e

• 5-letter words excluding w