Cryptic
Etymology
From Late Latin "crypticus", from Greek "kryptikos" (fit for concealing), from "kryptos" (hidden), the same root behind "crypt" and "encryption." Something cryptic is, by origin, buried — meaning stashed out of plain sight.
adjective · /KRIP-tik/
Having a hidden or obscure meaning; deliberately puzzling.
What it names
Obscurity that seems intentional — a message that hides its sense on purpose — rather than one that is merely unclear.
Example
His last text was cryptic — just a time and the word "maybe" — and she spent the evening decoding it.
Related idea
Cryptic suggests meaning deliberately concealed and awaiting a key; ambiguous means genuinely open to more than one reading — the cryptic hides one answer, the ambiguous offers several.