I simply call this link speed or L1 throughput; with Ethernet, this is the nominal speed.
You can directly calculate the maximum, effective L4 throughput for TCP over IPv4 over standard Ethernet (without any options) with (1460/1538) * link speed.
For completeness, the nominal speed doesn't include all Ethernet overhead. The physical layer encodes bits with various line codes, so for instance a 1000BASE-SX signal (1 Gbit/s over shortwave multi-mode fiber) is 8b/10b encoded with a physical signal rate of 1.25 Gbit/s.
You can find the nominal speed only in the physical layer's top sublayer (on top of PCS), but it's a very practical figure to work with.
While some might refer to the lower physical sublayer as L0, the only official use I know of is with Fibre Channel where FC-0 refers to the lowest part of the FC physical layer - PHYs, transceivers, cables and connectors. For Ethernet, this is (more or less) the PMD sublayer.