Definition - What does Host Adapter mean?
A host adapter is an item that connects a central hardware resource to an additional network or storage hardware. Different types of host adapters support different data transfer protocols, reflecting the advancement of data transfer setups.
A host adapter is also known as a host bus adapter (HBA).
Techopedia explains Host Adapter
A diversity of devices can be called host adapters. Many of them are traditional physical circuit board pieces that are installed in the host device. Some may be more portable or adaptable than others. Even hardware pieces used to connect USB devices can be called host adapters. Most of them will operate in fairly straightforward ways to set up "plug and play" functionality in broader network designs.