U+2718 Heavy Ballot X

The Wikipedia has the following information about this codepoint:

An X mark (also known as an ex mark or a cross mark or simply an X or ex or a cross) is used to indicate the concept of negation (for example "no, this has not been verified", "no, that is not the correct answer" or "no, I do not agree") as well as an indicator (for example, in election ballot papers or in maps as an x-marks-the-spot). Its opposite is often considered to be the O mark used in Japan and Korea or the check mark used in the West. In Japanese, the X mark (❌) is called "batsu" (ばつ) and can be expressed by someone by crossing their arms.

It is also used as a replacement for a signature for a person who is blind or illiterate and thus cannot write their name. Typically, the writing of an X used for this purpose must be witnessed to be valid.

Contrary to the negation or negative perception delegated to the letter X, there is a significant resilience in the usage displayed by the letter's placement. This unique letter is also recognized as the symbol of multiplicity, the Roman numerical symbol for 10, and also the mark of a forgotten treasure. As a verb, to X (or ex) off/out or to cross off/out means to add such a mark. It is quite common, especially on printed forms and document, for there to be squares in which to place x marks, or interchangeably checks.

It is traditionally used on maps to indicate locations, most famously on treasure maps. It is also used as a set of three to mark jugs of moonshine for having completed all distillation steps, while additionally signifying its potency (as high as 150 proof) relative to legal spirits, which rarely exceed 80 proof (40% ABV).

Among Native Americans in the 18th and 19th centuries, the X mark was used as a signature to denote presence or approval, particularly regarding agreements and treaties.