(mineralogy) A tetragonal-ditetragonal dipyramidal mineral containing barium, calcium, chlorine, fluorine, hydrogen, manganese, oxygen, silicon, and titanium.

(Scotland) purposeful

(chiefly music, language learning) To play (an instrument) or sing or to learn music without reading or memorizing sheet music; to learn a language without instruction. / To do by guessing, to impr...

present participle of caliper