noun
1. : a direct line of communication between heads of government ; broadly : any direct line of communication (as between an executive and employees)
2. : a usually toll-free telephone service available to the public for some specific purpose: as
a. : one by which callers can talk confidentially about personal problems to a sympathetic listener
a suicide hot line
b. : one by which callers can obtain free advice
a legal hot line
a grammar hot line
c. : one by which a citizen can report illegal activities (as to a government agency)