| 释义 |
sub·grade
\ˈsəb+ˌ-\ noun
Etymology: sub- + grade
1. : a subordinate level in a scale (as of rank or quality)
< subgrade is used in some classifications at a supraphylar level >
2. : a layer (as a stratum or surface) immediately beneath some principal layer; specifically : a surface of earth or rock leveled off to receive the foundation of a structure (as a road, pavement, building, sewer) or the ballast of a railroad |