base level
Definitions
The lowest point or level to which a stream can erode its bed.
A fundamental or starting level of performance, activity, or measurement from which further changes are calculated.
The lowest stratum or foundation upon which something is built or organized.
Examples
The mountain climber started her ascent from the base level of the valley.
We need to establish a base level of understanding before we can discuss the complex technical details.
Synonyms
foundation level starting point ground floor baseline fundamental level