Second lieutenant (called under-lieutenant in some countries) is a junior commissioned officer military rank in many armed forces.
Like the United Kingdom, the rank of second lieutenant replaced the rank of ensign and cornet in 1871. The rank of second lieutenant was phased out in the Australian Regular Army in 1986.
The Canadian Forces adopted the rank with insignia of a single gold ring around the service dress uniform cuff for both army and air personnel upon unification in 1968 until the late 2000s. For a time, naval personnel used this rank but reverted to the Royal Canadian Navy rank of acting sub-lieutenant, though the CF green uniform was retained until the mid-1980s. Currently, the Canadian Army insignia for second lieutenant is a pip and the Royal Canadian Air Force insignia for lieutenant is one thick braid. The equivalent rank for the Royal Canadian Navy is acting sub-lieutenant.
Since 1951 in the Israel Defense Forces (סגן-משנה (סג"מ segen mishne (sagam) has been equivalent to a second lieutenant (NATO OF-1). From 1948 – 1951 the corresponding rank was that of a (סגן) segen, which since 1951 has been equivalent to lieutenant. Segen mishne means "junior lieutenant" and segen literally translates as "assistant". Typically it is the rank of a platoon commander. Note that the IDF uses this rank across all three of its services.