|Noah Webster's Dictionary|
1. (n.) The quality or state of being single, or separate from all others; the opposite of doubleness, complication, or multiplicity.
2. (n.) Freedom from duplicity, or secondary and selfish ends; purity of mind or purpose; simplicity; sincerity; as, singleness of purpose; singleness of heart.
Singleness (3 Occurrences)
Acts 2:46 Day by day, continuing steadfastly with one accord in the temple, and breaking bread at home, they took their food with gladness and singleness of heart, (WEB KJV ASV WBS)
Ephesians 6:5 Servants, be obedient to those who according to the flesh are your masters, with fear and trembling, in singleness of your heart, as to Christ; (WEB KJV ASV WBS RSV)
Colossians 3:22 Servants, obey in all things those who are your masters according to the flesh, not just when they are looking, as men pleasers, but in singleness of heart, fearing God. (WEB KJV ASV WBS RSV)