sub·grade 
(sŭbgrād′)
(sŭbgrād′)n.
The level layer of rock or earth upon which the foundation of a road or railway is laid.
- Narmada
- Narraganset
- Narragansett
- Narragansett
- Narragansett Bay
- Narragansett turkey
- narratability
- narratable
- narrate
- narration
- narrational
- narrationally
- narrative
- narratively
- narrow
- narrow-bodied
- narrowcast
- narrowcaster
- narrow gauge
- narrow-gauge
- narrow-gauged
- narrowish
- narrowly
- narrow-minded
- narrow-mindedly