(mathematics, logic) Denoting the second in a numerical sequence of models, languages, relationships, forms of logical discourse etc. / Of secondary importance.

The orbit of a satellite that is nearer the planet than it would be if it were in synchronous orbit

(dated, 17th century) The principles under which the world and its components operate. / The strict enforcement of law, statutes, and social conventions.

A satellite orbit around the Earth within the altitude range of 200 - 2000 km, in which a satellite can communicate with Earth with a small time lag and energy consumption. Abbreviation: LEO.

(music) A large orchestra that traditionally plays Western classical orchestral music.

(biology) a male copulatory organ

Alternative form of what the doctor ordered

(pharmacology) A pill designed to disintegrate in the mouth.

(idiomatic) Exactly what is necessary or useful in a given situation; something very beneficial or desirable.

(calculus) An equation involving the derivatives of a function of only one independent variable.