(astronomy) A small autumn constellation of the northern sky, said to resemble an arrow. It lies between the constellations of Vulpecula and Aquila.

Relating to chemiatry; iatrochemical.

Any extinct marine reptile of the clade †Ichthyosauromorpha

(military, weaponry) a type of theoretical radiological nuclear weapon that relies on an induced rapid change in the state of nuclear isomers to generate an intense gamma ray flash.