Configuration Management Database (CMDB)
A database of configuration items (CIs) and their relationships, typically used to support ITSM.
A CMDB extends an asset inventory with relationship modelling: which service runs on which server, which user is in which department, which laptop runs which OS build.
CMDB and ITAM overlap but have different goals. ITAM cares about ownership and lifecycle; CMDB cares about service impact and change management.
In practice, smaller organisations start with ITAM and add CMDB-style relationships (location → asset → user → license) as their footprint grows.