Have you ever noticed that many four-letter words can be changed to five-letter words by inserting a letter in the middle of the word? For example, BUST can yield BURST; CAGE gives CADGE; and LIER offers LIFER, LINER, LITER, and LIVER.
Brang, Pamela H.
"Four Will Get You Five,"
Word Ways: Vol. 11
, Article 12.
Available at: https://digitalcommons.butler.edu/wordways/vol11/iss1/12