Alternatively it may commonly be a diminutive of Jacob, its French variant Jacques, or given names like Jackson which have been derived from surnames.

[2][4] Alternatively, it may be derived from an anglicisation of Jacques, the French form of the name James or Jacob.

[2] There is also a theory that it is Celtic in origin, meaning "healthy, strong, full of vital energy" (compare the Welsh word iach, "health"), from a putative Ancient British Yakkios.

Both the name and the word "jack" were long used as a term to refer to any man, especially of the common classes.

The name Jack is unusual in the English language for its frequent use as a noun or verb for many common objects and actions, and in many compound words and phrases.