impenetrable /im-penˈi-trə-bl/

1. Incapable of being penetrated
2. Impervious
3. Inscrutable
4. Occupying space exclusively (physics)

• neurilemma
• neurilemmas
• neurilities
• neurility
• neurine
• neurines
• neurism
• neurisms
• neurite
• neurites
• neuritic
• neuritics
• neuritis
• neuritises
• neuro-
• neuroanatomical
• neuroanatomies
• neuroanatomist
• neuroanatomists
• neuroanatomy
• neurobiological
• neurobiologies
• neurobiologist
• neurobiologists
• neurobiology