secret;  secrecy;  mystery;  secret (e.g. to success);  esoteric teachings
 to hide;  to keep to oneself
 (private) secretary;  treasured book;  secret book
 secret or hidden place;  female genitalia;  the underworld;  the other world
 hidden treasure;  treasured article
 behind closed doors;  behind-the-scenes;  (under the veil of) secrecy
 secret base;  hideout;  hidden position
 secret art;  the mysteries
 secret medicine;  secret remedy;  nostrum;  wonder drug;  excellent remedy
 secret plan;  secret scheme;  secret stratagem;  secret method
 secret (recipe, medicine, etc.);  mysteries (e.g. of an art)
 treasuring;  cherishing;  prizing;  holding dear
 secret (method, trick, etc.);  key (e.g. to success);  mysteries (of an art, trade, etc.);  recipe;  trick
 unexplored region;  secluded region;  place off the beaten track
 remaining silent;  keeping secret
 to keep secret;  to conceal
 secret method;  secret process;  secret formula;  esoteric rituals (in Shingon Buddhism)
 secret technique;  secret art
 company secret;  industrial secret;  trade secret
 to have (a) potential for ...;  to have it in one to do
 secret ceremony;  ritual;  sanctum sanctorum
 secret story;  unknown episode
 secret swordsmanship (of a specific school);  secret traditions of fencing
 right to keep silent;  right to silence;  right to remain silent
 closely-guarded secret;  top secret
 to keep to oneself;  to keep secret
 hidden mysteries;  secret principle
 classified information;  top secret
 favourite child;  favourite student;  apple of one's eye
 little-known hot spring;  secret hot spring;  secluded hot spring
 to betray a secret;  to reveal a secret
 confidential;  secret;  classified
 keeping a secret;  secrecy;  confidentiality
 secret meeting;  secret conference
 secretive;  mysterious;  furtive;  stealthy;  clandestine;  sneaky
 confidentiality;  nondisclosure
 password;  secret spell;  secret phrase
 esoterica;  mystery;  sanctum
 treasured book;  secret book;  pornographic book
 confidential document;  confidential paper;  classified document
 Buddhist image normally withheld from public view
 secret meeting;  secret conference;  closed-door session
 secret garden;  private garden;  name for female genitalia
 non-disclosure agreement;  NDA
 secret history;  hidden history;  unknown historical facts
 private records;  secret notes;  secret document;  confidential papers
 treasured picture;  secret picture;  obscene picture
 official test for a secretarial qualification
 secret method;  secret recipe;  (prescription for a) secret medicine
 government-paid secretary
 keeping (something) secret
 privacy of communications
 leaking of a secret;  leakage of a secret
 secluded station;  unexplored station
 secret vote;  secret ballot
 secret technique;  secret art
 Act on the Protection of Specially Designated Secrets (2013);  Secret Information Protection Act
 privacy of correspondence
 specially designated secret
 recording audio without consent;  secret recording
 secrets;  mysteries;  secret formula;  essence;  esoterica (of an art, martial arts, etc.)
 secret records;  secret document;  secret notes
 private key (cryptography);  secret key
 official test for a secretarial qualification
 secret key cryptography;  symmetric key cryptography
 secret will and testament;  sealed envelope will
 general secretary (esp. of Communist parties of Vietnam and the Democratic Republic of North Korea);  secretary-general
 Yalta Agreement (secret American-British-Soviet agreement wherein the Soviets agreed to attack Japan within three months of the German surrender; February 11, 1945)
 privilege (e.g. "attorney-client privilege")
 secure computation;  secure computing
 the crime of revealing a secret;  breach of confidence
 the crime of revealing a secret;  breach of confidence
 sacrament of penance and reconciliation
 (crime of) revealing state secrets;  charge of revealing national security information
 sacrament of penance and reconciliation