Hi Oatmeal,
Here are a few more translations that might help with the meaning of these words.
YLT
2Peter 1:5 And this same also--all diligence having brought in besides, superadd in your faith the worthiness, and in the worthiness the knowledge,
v. 6 and in the knowledge the temperance, and in the temperance the endurance, and in the endurance the piety,
v. 7 and in the piety the brotherly kindness, and in the brotherly kindness the love;
RSV
2Peter 1:5 For this very reason make every effort to supplement your faith with virtue, and virtue with knowledge,
v. 6 and knowledge with self-control, and self-control with steadfastness, and steadfastness with godliness,
v. 7 and godliness with brotherly affection, and brotherly affection with love.
Rotherham
2Peter 1:5 And, for this very reason also—adding, on your part, all diligence, supply, in your faith, excellence, and, in your excellence, knowledge,
v. 6 And, in your knowledge, self-control, and, in your self-control, endurance, and, in your endurance, godliness,
v. 7 And, in your godliness, brotherly affection, and, in your brotherly affection, love.
NKJV
2Peter 1:5 But also for this very reason, giving all diligence, add to your faith virtue, to virtue knowledge,
v. 6 to knowledge self-control, to self-control perseverance, to perseverance godliness,
v. 7 to godliness brotherly kindness, and to brotherly kindness love.
GNB
2Peter 1:5 For this very reason do your best to add goodness to your faith; to your goodness add knowledge;
v. 6 to your knowledge add self-control; to your self-control add endurance; to your endurance add godliness;
v. 7 to your godliness add Christian affection; and to your Christian affection add love.
CLV
2Peter 1:5 Now for this same thing also, employing all diligence, in your faith supply virture, yet in virtue knowledge,
v. 6 yet in knowledge self-control, yet in self-control endurance, yet in endurance devoutness,
v. 7 yet in devoutness brotherly fondness, yet in brotherly fondness love."
mercy, peace and love
Kat