fem. proper name, from Greek sōphrōnia, from sōphrōn (genitive sōphrōnos) "discreet, prudent, sensible, having control over sensual desires, moderate, chaste," literally "of sound mind," from sōs "safe, sound, whole" + phrēn "heart, mind" (see phreno-).
c. 1400, mediocrite, "moderation; intermediate state or amount," from Latin mediocritatem (nominative mediocritas) "a middle state, middling condition, medium," from mediocris "of middling height or state, moderate, ordinary," figuratively "mediocre, mean, inferior," literally "halfway up a mountain" (see mediocre). Neutral at first; disparaging sense "quality of being moderate or middling in ability, accomplishment, etc." began to predominate from late 16c. The meaning "person of mediocre abilities or attainments" is from 1690s. Before the tinge of disparagement crept in, another name for the Golden Mean was golden mediocrity.
1580s, "of moderate degree or quality, neither good nor bad," from French médiocre (16c.), from Latin mediocris "of middling height or state, moderate, ordinary," figuratively "mediocre, mean, inferior," literally "halfway up a mountain," from medius "middle" (from PIE root *medhyo- "middle") + ocris "jagged mountain" (cognate with Greek okris "peak, point," Welsh ochr "corner, border," Latin acer "sharp;" from PIE root *ak- "be sharp, rise (out) to a point, pierce"). As a noun, "mediocre thing or person," by 1834.
[T]here is an alarmingly wide chasm, I might almost say a vacuum, between the high-brow, who considers reading either as a trade or as a form of intellectual wrestling, and the low-brow, who is merely seeking for gross thrills. It is to be hoped that culture will soon be democratized through some less conventional system of education, giving rise to a new type that might be called the middle-brow, who will consider books as a source of intellectual enjoyment. ["The Nation," Jan, 25, 1912]
late 14c., "moderate, temperate" (a sense now obsolete), past-participle adjective from measure (v.) in the sense of "exercise moderation." Meaning "uniform, regular, characterized by uniformity of movement or rhythm" is from c. 1400. That of "ascertained or determined by measuring" is from mid-15c. Meaning "deliberate, restrained" is from 1802.