(physics) The lightest and most common isotope of hydrogen, having a single proton and no neutrons: ¹₁H / An atom of this isotope.

A group of cells in the outer wing of insects that have the appearance of a pterostigma

A Gael; a member of the Goidelic division of Celtic languages as opposed to the Brythonic division.

Sad because of a disappointment. / (obsolete, of a horse) Having the crest, or upper part of the neck, hanging to one side.