-n't shortened (enclitic) form of not¹

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)

• is
• is-
• IS
• Is.
• ISA
• Isa.
• isabel
• isabella
• isabelline
• isabels
• isagoge
• isagoges
• isagogic
• isagogics
• isallobar
• isallobars
• isapostolic
• isatin
• isatine
• isatines
• isatins
• Isatis
• I say
• ISBA
• ISBN