Meaning
A temporary period prior to a major release during which no new code changes may be added to the codebase.
Three examples from work
Release schedule
PMReminder: code freeze starts tomorrow at 5 PM sharp.
DevUnderstood, all pending PRs will be merged before noon.
Scope exception
DevCan we get an exception to merge this styling update during code freeze?
QA LeadNo exceptions unless it fixes a blocker; stability is our priority.
Holiday preparation
VPWe will have a strict two-week code freeze over the Christmas holidays.
LeadThat guarantees peace of mind for the on-call engineers.
Use phrases like 'enter code freeze' or 'lift the code freeze'. During code freeze, only critical bug fixes with management approval may merge.