Mansplaining is a portmanteau of the word man and the informal form splaining of the verb explaining and means "to explain something to someone, characteristically by a man to woman, in a manner regarded as condescending or patronizing". Lily Rothman of The Atlantic defines it as "explaining without regard to the fact that the explainee knows more than the explainer, often done by a man to a woman", and feminist author and essayist Rebecca Solnit ascribes the phenomenon to a combination of "overconfidence and cluelessness".
Many people consider the term to be pejorative, sexist and patronising to men. Its use remains controversial and people who use it may find themselves categorised as sexist and a misandrist. Because of this some moderate feminists consider the term unhelpful to feminism and advocate for its use to be stopped.
Solnit's original essay went further, discussing the consequences of this gendered behavior and drawing attention to its effect in creating a conspiracy of silence and disempowerment. Solnit later published Men Explain Things To Me, a collection of seven essays on similar themes. Women, including professionals and experts, are routinely seen or treated as less credible than men, she wrote in the title essay, and their insights or even legal testimony are dismissed unless validated by a man. She argued that this was one symptom of a widespread phenomenon that "keeps women from speaking up and from being heard when they dare; that crushes young women into silence by indicating, the way harassment on the street does, that this is not their world. It trains us in self-doubt and self-limitation just as it exercises men's unsupported overconfidence."
Mansplaining differs somewhat from other forms of condescension in that it is specifically gender-related, rooted in a sexist assumption that a man will normally be more knowledgeable, or more capable of understanding, than a woman.
Splaining and the verb splain have existed for more than 200 years and were originally simply colloquial pronunciations of the words explaining and explain. Since some time before the first written evidence in 1989 of a shift in meaning, they have increasingly referred to condescending and often extensive or verbose explanations. Since then, the word has been increasingly prefixed by words to refer to who is doing the splaining, of which mansplaining was the first. This remains the best known form of splaining, and it has inspired terms for many more, but in some cases the term is also or mostly used in the original positive sense of "explaining", for example gaysplaining.