Definition of N.b.

Noun

• a Latin phrase (or its abbreviation) used to indicate that special attention should be paid to something
  "the margins of his book were generously supplied with pencilled NBs"
  - nota bene - nb

Word games points for the N.b.

• Scrabble® score of the n.b. (4)
• Word Chums® score of the n.b. (6)
• Words With Friends® score of the n.b. (6)