- natural density
- natural derivation
- natural domain (= natural domain of definition)
- natural domain of existence
- natural duality
- natural embedding
- natural enumeration
- natural epimorphism
- natural equation
- natural equivalence
- natural exponent
- natural extension
- natural filter
- natural filtration
- natural form
- natural formulation
- natural frame
- natural frequency
- natural generalization
- natural geometry
- natural homomorphism
- natural independence phenomenon
- natural index
- natural injection
- natural invariant