The word is recorded from Old English (in form endleofon), and comes from the base of one + a second element, probably expressing the sense ‘left over’ and occurring also in twelve. The phrase the Eleven is used to designate the original Apostles, without Judas.
eleven-plus in the UK, an examination taken at the age of 11–12 to determine the type of secondary school a child should enter; the examination is now limited to a few local education authority areas.
give us back our eleven days a slogan used in protest against the adoption of the Gregorian Calendar in 1752, when the date moved directly from 2 to 14 September. In this form it is associated with Hogarth's cartoon showing a rowdy Oxfordshire election of 1754.
up to eleven in informal usage, up to maximum volume; with reference to a scene in the film This is Spinal Tap (1984), featuring a supposedly louder amplifier with control knobs having 11 rather than 10 as the top setting.
See also nine-eleven, rain before seven, fine before eleven.