flex [E16th] This comes from the Latin flectere ‘to bend’. The electrical flex [E20th] is a shortening of flexible cord or cable, flexible and flexibility being Late Middle English and from the same source, as is deflect [M16th] ‘bend away’. An inflection [LME] was originally an act of bending inwards, gaining its grammatical sense in the mid 17th century. Flexitime has been being worked, by those lucky enough to get it, since the 1970s.