a. [f. L. āer air + -FORM. Cf. Fr. aériforme.]
1. Of the form of air or vapor, gaseous.
1620. Bacon, Nov. Org., II. vii. 455. Whether that spirit is … fine or coarse, aeriform or igniform, active or sluggish.
1782. Kirwan, in Phil. Trans., LXXII. 209. Which, when fixed and concrete, is called phlogiston, and, when rarified and aëriform, inflammable air.
1822. Imison, Sc. & Art, I. 126. Pneumatics is the science which treats of the mechanical properties of elastic or aeriform fluids.
1860. Piesse, Lab. Chem. Wonders, 125. Gases which are only known to exist in an aëriform state.
2. fig. Unsubstantial, intangible, unreal.
1828. Carlyle, Misc. (1857), I. 176. The figures light and aëriform, come unlooked for, and melt away abruptly. Ibid. (1831), Sart. Res. (1858), 104. Or Man’s Activity and Attainment the chief results are aeriform.
3. quasi-sb. An aeriform fluid; a gaseous body.
1865. Macvicar, in Reader, No. 147. 462/3. The volumes of aëriforms.
