indefinable /in-di-fīˈnə-bl/

1. That cannot be defined
2. Hard to identify or describe

indefinˈableness noun

indefinˈably adverb

• top dog
• top dogs
• top-down
• top drawer
• top-drawer
• top drawers
• top-dress
• top-dressed
• top-dresses
• top dressing
• top-dressing
• top dressings
• tope
• topectomies
• topectomy
• toped
• topee
• topees
• topek
• top-end
• toper
• to perfection
• topers
• topes
• top flight