Puisne Judge

A puisne judge or puisne justice (/ˈpjuːni/; French: puisné or puîné, "junior") is a regular member of a court other than the court's chief judge or chief justice, or any ex officio member of the court (e.g. the Chancellor of the High Court with respect to the Court of Appeal of England and Wales).

The term is used almost exclusively in common law jurisdictions such as the jurisdiction of England and Wales within the United Kingdom, Australia, including its states and territories; Canada, including its provinces and territories; India and its constituent states; the British possession of Gibraltar; Kenya; Sri Lanka; and Hong Kong.

The term puisne judge/justice is not used by the United States, notwithstanding its being a common law jurisdiction; nor by any of its 56 constituent states, territories or federal district - 51 of which are common law jurisdictions, and 3 of which are quasi-common law jurisdictions. Instead, the term associate justice is used by the United States Supreme Court, the DC Court of Appeal, and by most state and territorial high courts. The term associate judge is also used throughout the United States, but this frequently means something different from puisne or associate justice.
This is in keeping with standard American legal practice of utilizing uniquely-American legal terminologies within the American transition of its primarily English Common Law-based system, but which includes and respects the U.S. system's Scottish, Spanish and French influences, within the context of, and subsequent to, the American Revolution.

...
Wikipedia