A surname originating as an occupation

A nickname for both the 4-8-0 and (though incorrectly) the 4-10-0 train configurations.

Prepended to a boy's name or surname as a (now somewhat formal) form of address. / A religious teacher, often as an honorific title. / The title of the head of certain colleges and schools.

(Wicca) One of the triune gods of the Horned God in Wicca alongside the Father and Sage and representing a boy or a young man / (banking) MasterCard

A person with an extraordinary intellect or skill that is markedly superior to his or her peers. / A person responsible for the highest level of planning and execution of a major operation.

To act in the role of mastermind.

(especially Nazism) A race of people who are superior to others.

The mastoid process.

The conical, nipple-like projection of the petrous part of the temporal bone, that is situated behind the ear in humans and many other vertebrates, and serves as a site of muscle attachment.

(anatomy) Being the process of the temporal bone behind the ear. / (zootomy) Being any of several bony elements that occupy a similar position in the skull of lower vertebrates.