The 10th edition of Systema Naturae was a book written by Carl Linnaeus and published in two volumes in 1758 and 1759, which marks the starting point of zoological nomenclature. In it, Linnaeus introduced binomial nomenclature for animals, something he had already done for plants in his 1753 publication of Species Plantarum.

Before 1758, most biological catalogues had used polynomial names for the taxa included, including earlier editions of Systema Naturae. The first work to consistently apply binomial nomenclature across the animal kingdom was the 10th edition of Systema Naturae. The International Commission on Zoological Nomenclature therefore chose the 1st of January 1758 as the "starting point" for zoological nomenclature, and asserted that the 10th edition of Systema Naturae was to be treated as if published on that date. Names published before that date are unavailable, even if they would otherwise satisfy the rules. The only work which takes priority over the 10th edition is Carl Alexander Clerck's Svenska Spindlar or Aranei Suecici, which was published in 1757, but is also to be treated as if published on January 1, 1758.

The book Systema Naturae (sometimes written Systema Naturæ with the ligature æ) was one of the major works of the Swedish botanist, zoologist and physician Carolus Linnaeus. The first edition was published in 1735. The full title of the 10th edition, which was the most important one, was Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis or translated: "System of nature through the three kingdoms of nature, according to classes, orders, genera and species, with characters, differences, synonyms, places".

The tenth edition of this book is considered the starting point of zoological nomenclature. In 1766–1768 Linnaeus published the much enhanced 12th edition, the last under his authorship. Another again enhanced work in the same style and entitled "Systema Naturae" was published by Johann Friedrich Gmelin between 1788 and 1793. Since at least the early 1900s zoologists commonly recognized this as the last edition belonging to this series. It was also officially regarded by the International Commission on Zoological Nomenclature in Opinion 296 (26 Oct 1954) as the 13th edition of Systema Naturae.

A stereotypical cat lady, or cat woman, is a singlewoman who dotes upon her cat or cats. The term is usually considered pejorative, though it is sometimes embraced.

At least in the Anglosphere, single women who own cats have long been associated with the concept of spinsterhood. In more recent decades, the concept of a cat lady has been associated with "romance-challenged (often career-oriented) women who can't find a man".

The term is also used to denote an animal hoarder who keeps large numbers of cats without having the ability to properly house or care for them. They may be ignorant about their situation.

The 2009 documentary Cat Ladies tells the stories of four women whose lives have become dedicated to their cats. The film was directed by Christie Callan-Jones and produced by Chocolate Box Entertainment, originally for TVOntario. It was an official selection at the 2009 Hot Docs Festival, Silverdocs Festival, and San Francisco's DocFest.

Naftali Berrill, Ph.D., Director of the New York Center for Neuropsychology and Forensic Behavioral Science told AOL Health, "These may be people who have a very hard time expressing themselves to other people. They may find the human need for affection is met most easily through a relationship with a pet." This devotion can sometimes signal mental or emotional issues such as depression.