TACACS
securityTerminal Access Controller Access-Control System — a family of protocols that handle remote authentication and related services for network access.
Pronunciation
Correct
TAK-aks
/ˈtækæks/
Pronounced as two syllables: TAK-aks. The modern version TACACS+ is pronounced the same way. Cisco documentation confirms this pronunciation.
Source: www.rfc-editor.org(official spec)