To lock an evolving software distribution or
document against changes so it can be released with some hope of
stability. Carries the strong implication that the item in
question will `unfreeze' at some future date. "OK, fix that
bug and we'll freeze for release."
There are more specific constructions on this term. A `feature
freeze', for example, locks out modifications intended to introduce
new features but still allows bugfixes and completion of existing
features; a `code freeze' connotes no more changes at all. At
Sun Microsystems and elsewhere, one may also hear references to
`code slush' -- that is, an almost-but-not-quite frozen state.