codeword

noun

1. 1

   A string representing an encoded piece of text.

   “Bob cannot get any information out of the codeword since he doesn't know what transmission bases Alice used.”

2. 2

   A word or phrase (or by extension a concept) used to make a (concealed) reference to another word or concept.

3. 3

   A type of crossword puzzle where individual letters are represented by numbers and the solver must identify them by their position and frequency.