Here is the word in a sentence: The client implementation strategy involved a "cold-cut over".

It's not on the internet, anyone ever heard this term before?

Haven't heard it phrased quite like this, but, being in the tech field, my guess is that client is going from one system to another (data network, phone system, software package). Normally, for safety, we like to bring the new system up in parallel to the old, verify/validate functionality, then "cut over" to the new system. Looks to me like the vendor is betting this will work and is just cutting over with no fallback/redundancy. Depending on the circumstances, this may be all well and good.
Bill

Depends on the context and the business the client is in. This term is used with data storage and also machinery. Do you know more about the business?