A surname.

The quotient of a Hilbert space by an equivalence relation which considers a pair of vectors equivalent iff they differ only by a factor which is a complex number.

(mathematics) A vector space which is additionally equipped with a norm.

(mathematics) A vector space which is additionally equipped with an inner product.

A natural phenomenon picked up as a radio signal from outer space, and sounding like a loud hiss.

The dark space in a glow discharge that is adjacent to the cathode.

The dark space in a glow discharge that is between the negative glow and the positive column.

The dark space in a glow discharge between the cathode glow and the negative glow.

The official name of Spain.

Melospiza melodia, a medium-sized American sparrow.