Final answer:
While 'Jackal' is not a known brevity code from the Navajo Code Talkers, brevity codes like 'iron fish' for submarine were used by them during World War II. Their code, which turned the Navajo language into an unbreakable cipher for important military communication, had significant impact and remained unbroken throughout the war.
Step-by-step explanation:
The term "Jackal" as a brevity code word does not specifically relate to the Navajo Code Talkers that you've mentioned in the historical context of the question.
However, it's important to understand the significance of brevity codes and how similar methodologies were used during World War II by the Code Talkers. Brevity codes are designed to convey complex information with single words or phrases. Although "Jackal" is not a known brevity code used by the Navajo Code Talkers, brevity codes such as "iron fish" for submarine were indeed part of their innovative communication strategy.
The Navajo Code Talkers created a unique and secure means of communication during the war, using their native language to represent military terms. Their code was never broken by German or Japanese intelligence, despite efforts to decipher it. If brevity code "Jackal" is being used in another context, it would typically relate to a specific, prearranged meaning agreed upon by the users of the code.