A word or phrase (or by extension a concept) used to make a (concealed) reference to another word or concept.
A string representing an encoded piece of text.
A type of crossword puzzle where the letters of the alphabet are represented by numbers and the solver must identify them by their position and frequency.
Something trifling, or of no consequence or importance.
A trivial remark especially in the term sweet nothings.
A nobody (insignificant person).
Not any thing; no thing.
An absence of anything, including empty space, brightness, darkness, matter, or a vacuum.