micrometre
(ˈmaɪkrəʊmiːtə(r))
Also (U.S.) -meter.
[f. micro- 5 a + metre n.2]
A millionth of a metre: = micron.
The word has only recently become common (cf. quot. 1968), and now forms part of the International System of Units.
| 1880 Jrnl. R. Microsc. Soc. III. 327 The same reasoning..leads us, however, to recommend the adoption of ‘micrometre’ instead of ‘micromillimetre’, which would secure the uniformity desired, besides being a more convenient word. 1966 Kaye & Laby Tables Physical & Chem. Constants (ed. 13) 2, µ is widely employed as an abbreviation of µm (10-6 m or micrometre) and is then called micron. 1968 Nature 16 Nov. 651/2 By resolution No. 7 the conference [sc. the thirteenth General Conference of Weights and Measures] decided to proscribe further use of the name ‘micron’, with the symbol µ attributed to this name, for the millionth part of the metre. The symbol µ is now the recognized prefix for the decimal sub-multiple 10-6 and the appropriate name for the millionth part of the metre is ‘micrometre’, with symbol µm. 1971 I. G. Gass et al. Understanding Earth xiv. 336/1 (caption) The amplitude..used for determining the magnitude is half the displacement between the two arrows—in this case 5 micrometres. 1973 Physics Bull. Nov. 662/3 They contain solid particles..with dimensions of about a tenth of a micrometre, a mass of 10-15 g each. 1974 Sci. Amer. July 45 (Advt.), Neutron radiography can resolve a few micrometers. |