Not an orthographic neighbor which substitutes one letter but the addition of a letter known as affix.....a letter placed at the beginning (pre-fix) or ending (suffix) of a root word to modify the meaning.
Many wordsmith's are crossword, worldle or other word game gurus as words, anything linguistic, are "their thing."
Often an additional one letter can change the meaning entirely.
Think, cab to scab
On the other hand, one letter emphasizing the word by giving it a name.
God's "word" becomes "sword" of the spirit. (Ephesians 6:17)
This past week as I was continuing my meditation on the Lord's Prayer from Matthew 6, I saw the word evil in a new light---or more like darkness.
Evil has a name. Add a d. Evil's name is devil.
Be watchful. The devil is an adversary. The devil prowls. The devil seeks to devour. Resist him. He is not good.(1 Peter 5:8-9)
Who is GOOD? Drop an O to know.
GOD is good. He will restore, confirm, strengthen and establish you through His Word. (1 Peter 5:10)
Against the evil wiles of the devil,....
use God's Word as your Sword of defense!