неизвестные неизвестные

unknown unknowns (противопоставляются "известным неизвестным" (known unknowns) – тем вещам, про которые мы знаем, что мы их не знаем A.Rezvov)

unknown unknowns (things we don’t know we don’t know –

goo.gl Artjaazz)

неизвестные неизвестные: 638 phrases in 96 subjects

Algebra	2
Alternative dispute resolution	2
American usage, not spelling	1
Artillery	1
Astronautics	6
Astronomy	1
Automated equipment	4
Aviation	5
Biology	1
Bookish / literary	2
British usage, not spelling	1
Business	1
Cardiology	2
Cartography	3
Chemical industry	1
Chemistry	3
Chess	5
Chromatography	1
Cinematography	1
Clinical trial	1
Combustion gas turbines	1
Computer networks	3
Computers	2
Construction	4
Contextual meaning	1
Cryptography	4
Diplomacy	3
Drilling	1
Ecology	1
Economy	1
Electronics	8
Energy industry	1
Epidemiology	1
Equestrian sports	1
European Union	2
Figurative	3
Firefighting and fire-control systems	1
Food service and catering	1
Forestry	1
General	157
Genetics	2
Geology	3
Geophysics	1
Historical	1
Idiomatic	3
Informal	3
Information security and data protection	4
Information technology	50
Internet	3
Journalism terminology	1
Latin	2
Law	7
Librarianship	8
Linguistics	3
Makarov	54
Management	1
Mass media	8
Mathematics	63
Mechanic engineering	1
Mechanics	5
Medical	41
Meteorology	5
Metrology	3
Microelectronics	1
Microsoft	12
Military	5
Mobile and cellular communications	1
Nanotechnology	1
Nautical	1
Obsolete / dated	2
Oncology	2
Operation systems	1
Patents	6
Pharmacy and pharmacology	1
Physics	2
Poetic	1
Politics	3
Production	1
Programming	31
Psychology	5
Quotes and aphorisms	1
Religion	1
Sakhalin	1
Saying	1
Scientific	2
Security systems	3
Shipbuilding	2
Slang	14
Software	1
Sports	1
Statistics	2
Technology	11
Telecommunications	5
Telephony	1
United States	2
Vulgar	1