A dictionary of Confusable Phrases: More Than 10,000 Idioms and Collocations

black book • little black book
black book —
1
. a register listing persons that have committed
offences against morality, etc.: The German government was
in a position to blackmail 47,000 prominent British “perverts”
whose names figured in a “black book.” Cf.: be in someone’s
black books — be out of favor with a person: Beatrice managed
to leave a very uncomfortable impression upon me and it was
clear that I was in her black books again. 2. an official book
offering special information: Rules relating to naval affairs are
still preserved in the black book of the admiralty.
little black book —
1
. a book containing the names of ac-
quaintances, potential dates, partners, etc.: I’ve got a nice
collection in my little black book. 2. a book for recording per-
sonal or private information: Evans kept a note of his expen-
diture in a little black book.
Note: 
Neither expression correlates in meaning with the phrase
black-letter book—a book printed in the old heavy Gothic style
of type: She saw Sir John seated by the fireplace, reading out
of a great black letter book.
black box • dark box
black box —
1
. a flight recorder in an aircraft : The flight
recorder is an indestructible “black box” which automatically
records the key functions in the aircraft. 2. any apparatus of
unknown internal design: Crime squads are searching for the
manufacturer of a black box which contains a device that can
reverse electricity meter readings. 3. (Austral.) a tree with nar-
row, grey-green leaves and rugged, dark grey bark: Other com-
munities contain species that are at the extremes of their nat-
ural distribution, such as black box (Eucalyptus largiflorens).
dark box —a container from which light is wholly excluded
(used for storing light-sensitive plates, etc.): Diaphanoscope —
a dark box constructed for exhibiting transparent photographs.