Something described as cryptic has or seems to have a hidden meaning, or is difficult to understand.

// The singer posted a cryptic message on her social media accounts, and fans raced to decipher it.

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"When Neon first met with 'Longlegs' writer-director Osgood Perkins, [chief marketing officer, Christian] Parkes' team pitched a cryptic viral ad campaign that put viewers in the perspective of Maika Monroe's detective. ... 'We give the audience these clues that they can piece together to unlock the mystery of the film,' Parkes explains." — Tim Grierson, The Los Angeles Times, 2 Jan. 2025

The history of cryptic starts with krýptein, a Greek word meaning "to hide or conceal." Can you uncover other krýptein relatives in English? Not surprisingly, crypt, meaning "underground chamber," is one, as is the name of the element krypton. Krýptein also gave us several words having to do with secret codes, such as cryptogram ("a communication in cipher or code") and cryptography ("the coding and decoding of secret messages"). And cryptocurrency is currency that exists digitally and that relies on computer encryption (secret code) to prevent counterfeiting and fraud.