tuoistõn

Perhaps a fossilized earlier genitive form of tuoi (“second”) (modern genitive form – tuoiz). Compare Estonian üksteist (“eleven”) a shortening of üksteistkümmend "one of the second ten" where "ten" gets dropped and "one of the second" remains.

• IPA^(key): /ˈtuoistən/, [ˈt̪ŭ̯o̯iˑst̪ən]

tuoistõn

1. teen (a set of objects of unspecified quantity ranging from 11 to 19)
   • Tiit-Rein Viitso; Valts Ernštreits (2012–2013), “tuoistõnd”, in Līvõkīel-ēstikīel-lețkīel sõnārōntõz [Livonian-Estonian-Latvian Dictionary]‎^[1] (in Estonian and Latvian), Tartu, Rīga: Tartu Ülikool, Latviešu valodas aģentūra

     tuoistõnd sizālõ

     in the teens

LĒL lists only a plural form (tuoistõnd). Both singular and plural are given in the declension table in this entry. Perhaps by error the declension type used for ordinals of teens (tuoistõnz (“teenth”)) is given in LĒL, evidently tuoistõn would have the same declension type as its simple compounds, e.g., kakštuoistõn, which is given above.

• tuoistõnz