O.E.
middel, from W.Gmc.
*middila (cf. M.L.G., Du.
middel), from P.Gmc.
*medjaz (see
mid).
Middle age "period between youth and old age" is attested from 1377;
middle aged first recorded 1608.
Middle Ages "period between ancient and modern times" (formerly roughly 500-1500 C.E., now more usually 1000-1500) is from 1616, translating L.
medium ævum (cf. Ger.
mittelalter, Fr.
moyen âge). First record of
middle class is from 1766; as an adj., "characteristic of the middle class" (depreciative) it dates from 1893.
Middle name first attested 1835, Amer.Eng.
Middlebrow first recorded 1925.
Middleman in the trading sense is from 1795;
middle management is 1957.
Middle-of-the-road in the fig. sense is attested from 1894; in old times, edges of the dirt road could be washed out and thus less safe.
[mid-l] 
adjective, noun, verb, -dled, -dling.
) (in the history of a language) intermediate between periods classified as Old and New or Modern: Middle English.