maven

an expert in a particular subject

Dave knows everything there is to know about computers. He's an expert, a whizz, a virtuoso, a genius, an authority, a buff, a wizard or a … maven?

the word is simply another way of describing a person who is an expert in a particular field

Though the word maven is less familiar in British English, it's been in mainstream use in the US for some years. It is simply another way of describing a person who is an expert in a particular field, and although it might not be the first noun that pops into our heads when we want to describe someone as extremely knowledgeable, it has been gaining ground in written form across the English-speaking world, especially in journalistic contexts.

The word maven usually occurs as the second part of a compound noun, with the modifying (i.e. 'first') noun specifying the subject on which the person described is an expert. Among the most common occurrences are compounds such as marketing maven and fashion maven, but other typical collocates include design, theatre/theater, style, money, and finance.

There is a small amount of evidence for informal use of a derived noun mavenhood (the quality or state of being a maven). Here's an example:

Background – maven

The word maven comes from Hebrew mebîn and Yiddish meyvn meaning 'someone who understands'. The word first came into American English in the 1960s, popularized between 1964 and 1969 by TV and radio commercials for Vita Herring (the flagship product of US company Vita Food Products Inc.), which featured a catchy jingle and enthusiastic recommendations from a herring connoisseur dubbed The Beloved Herring Maven. The word gained further exposure in the 1980s by US journalist William Safire, a former columnist for the New York Times, who regularly wrote about language-related topics and referred to himself as the language maven. More recently, Maven was the name given to an artificial opponent created for a computer version of the popular word game Scrabble®.