Final answer:
Pope Leo XIII's encyclical is known as 'Rerum Novarum' in both English and Latin, and was distributed on May 15, 1891.
Step-by-step explanation:
The English and Latin names for Pope Leo XIII's encyclical are Rerum Novarum and Rerum Novarum, respectively. This encyclical, which focused on the rights and duties of capital and labor, was distributed on May 15, 1891. It is an important document in the history of the Catholic Church because it addressed the condition of the working classes at a time when industrialization was changing the face of economies and societies across the world.