NT

1. National Theatre (now known as RNT)
2. National Trust
3. New Testament
4. Northern Territory (Aust)
5. Northwest Territories (of Canada)
6. No trumps (cards)

-n't shortened (enclitic) form of not¹

• unsuccessful
• unsuccessfully
• unsuccessfulness
• unsuccessive
• unsuccoured
• unsucked
• unsued-for
• unsued-to
• unsufferable
• unsufficient
• unsuit
• unsuitabilities
• unsuitability
• unsuitable
• unsuitableness
• unsuitablenesses
• unsuitably
• unsuited
• unsuiting
• unsuits
• unsullied
• unsummed
• unsummered
• unsummoned
• unsung