Thrithing, or Trithing

Thrithing, or Trithing [ðriðing (Saxon)]
the third part of a county or wapentakes, such as are the divisions, called Laths in Kent; Rapes in Sussex, and Ridings in Yorkshire.

Definition taken from The Universal Etymological English Dictionary, edited by Nathan Bailey (1736)

Thripples * Tin-worm
Swing
Taˊddy
Taˊmy
Teˊllers [in the Exchequer]
Teˊrrae-filius [i. e. the Son of the Earth]
Thinking
Thiˊrdendeal
Thor
Thripples
Thrithing, or Trithing
Tin-worm
Tithing-Men
Tower
Hollow Tower [in Fortification]
Towers [in Coat Armour]
Towˊering long sought [in Cattle]
Train
Train [in Watch-work]
Transpaˊrent Bodies [with Philosophers]
Trinity-House