septimation

Latin septimus (“seventh”) +‎ -ation, after decimation; compare septimate.

• (Received Pronunciation) enPR: sĕptĭmāʹshən, IPA^(key): /sɛptɪˈmeɪʃən/
• (US) IPA^(key): /ˈsɛptəmeɪʃən/

septimation

1. (rare) The loss, seizure, destruction, or killing of one seventh (of something or of a group).
   • 1844, J.A.T., “Observations on the Genius of the Christian Sabbath, as Illustrated in the Life of Wilberforce” in The Oberlin Evangelist VI, № 5, page 40

     To Wilberforce ‘the Sabbath was a delight’ […] O how often, even among those who most punctiliously observe it, does it seem […] an unwelcome exaction, a sort of septimation of time, as grievous as church decimations of property.

   • 1853, William Jackman [aut.] and I. Chamberlayne [ed.], The Australian Captive, chapter XVII, page 206

     We had gone into the enemy’s ground with seven hundred warriors — a little over one hundred of whom were missing when we left it — as, at that time, we could hardly muster six hundred. This septimation of our men was accompanied by a proportionate riddance of such encumbrances of the expedition as wore the shape of women and little ones.

• (proportionate reduction, by single aliquot part): quintation (1/5), decimation (1/10), vicesimation (1/20), tricesimation (1/30), centesimation (1/100)