CREST is The Council for Registered Ethical Security Testers, which is an UK organisation.
CPS: Cyber Physical System
CPS is an acronym that stands for Cyber Physical System. Essentially it means any digital device which interacts with the physical world. It is an overarching term that includes Operational Technologies (OT) and Robotics, amongst other things.
CPNI: Centre for the Protection of National Infrastructure
The Centre for the Protection of National Infrastructure or CPNI is run by the UK Goverment for the safety and security of UK Critical National Infrastructures.
Cipher / Cypher
A cipher (or cypher) is an algorithm that is used for the encryption/decryption of data.
CISSP: Certified Information Systems Security Professional
A Certified Information Systems Security Professional is often referred to as CISSP. It is a certification administered by the International Information System Security Certification Consortium, which is also known as (ISC)².
CiSP: Cyber Security Information Sharing Partnership
The CiSP is the Cyber Security Information Sharing Partnership which is an NCSC scheme in the United Kingdom.
CISO: Chief Information Security Officer
Chief Information Security Officer is usually represented by the acronym CISO.
CISOs exist in a large number of organisations, typically larger enterprises, and they generally look after the cyber security and privacy aspects of an organisation.
CIP: Critical Infrastructure Protection
The acronym CIP is used for Critical Infrastructure Protection. It is typically for the safety and security (not just cyber) of Critical National Infrastructures (CNI).
In the United Kingdom, the physical safety and security of CNI is looked after by the CPNI. The cyber security aspects of CNI are looked after by NCSC in the UK.