all clear

1. 1.

   a signal (usually a siren) that danger is over

   Broadersignal
2. 2.

   permission to proceed because obstacles have been removed

   Broaderpermission

Questions about all clear

What does all clear mean?

all clear means "a signal (usually a siren) that danger is over". That is the primary sense; the word has 2 in total, listed in full on this page.

Is all clear a common word?

all clear is banded "Uncommon" — turns up in careful writing rather than conversation. The band comes from how often the word appears in a large corpus of everyday English, not from an editor's impression.