- Implied
- Implied or indirect
- Inexplicit
- Inherent
- Suggested but not directly expressed
- Understood, yet not actually stated
- Infolded; entangled; complicated; involved.
- Congenital
- Deep rooted
- Inborn
- Inborn or natural
- Inherent
- Inherited
- Instinctive
- Indigene
- Indigenous
- Inhabitant
- Inherent
- Local alternative is too much!
- Resident
- Arising by birth; having an origin; born.
- Absolutely necessary
- Crucial
- Fundamental
- Inherent
- Linchpin
- Must-have
- Necessary
- Inherent
- Reason, ... cause
- Lying under or beneath; hence, fundamental; as, the
underlying strata of a locality; underlying principles.