undec

From un (“one”) +‎ dec (“ten”).

undec m or f (ordinal undecvet)

1. eleven
   • c. 1180, Cynddelw, Gwelygorddau Powys; quoted in William Owen Pughe, A Dictionary of the Welsh Language, Explained in English;: With Numerous Illustrations, from the Literary Remains and from the Living Speech of the Cymmry:, volume 2, London: E. Williams, 1803, page c. p585 s.v. Undegved:

     Undeg vad awen; undegved awyz
      A weinyz vy nhynged,
     O’m gwawd ran, o’m ban, o’m barzged,
     O walç valç, o Weilçiawn giwed.

     Eleven godly themes; the eleventh with my destiny will produce, with respect to my share of praise, of my elevation, of my bardic treasure, from a towering battlement, from the Gweilçion tribe.

   • traditional, ascribed to Taliesin, Yr awdl fraith, republished in Hugh James Rose and Samuel Roffey Maitland [eds.], The British Magazine, and Monthly Register of Religious and Ecclesiastical Information, Parochial History, and Documents Respecting the State of the Poor, Progress of Education, &c., volume 19, 1841, page 665:

     Naw cànt dau undeg wyth
     Y bu yn ymlwyth
     Yn arwain mysg-lwyth,
      Masgl a fæmina.

     Nine hundred and thirty years   [lit.: Nine hundred, two eleven, and eight]
     They existed sorrowing,
     Bearing a mixed-race,
      Male and female.

• Welsh: undeg