pref., treated as a euphonic form of BI- pref.2, used before vowels. Not found in L.: it seems to have originated in Fr. with the word binocle, which was probably formed from L. bīnī two together, a pair of (boves bini a pair of oxen yoked together). From binocle, binocular, bin- has been extended in English to other words, esp. chemical compounds (see BI- pref.2 III) as binacetate, biniodide, binoxalate, binoxide (for which Fr. has bioxyde). The phonetic analogy of a- an, co- con-, has probably influenced this Eng. use.
1808. Wollaston, in Phil. Trans., XCVIII. 100. The common binoxalate, or salt of sorrel.
1810. Henry, Elem. Chem. (1826), II. 107. Binacetate of copper.
c. 1860. Faraday, Forces Nat., iii. 3. 195, note. Binoxide of nitrogen.
c. 1865. J. Wylde, in Circ. Sc., I. 375/1. The proto-, and biniodide.
