thirdly(r = adv.all) third - in the third place; "third we must consider unemployment"

   In the third place. Bacon. [1913 Webster]

N  triplication, triplicity, trebleness, trine, treble, triple, tern, ternary, triplicate, threefold, trilogistic, third, trinal, trine, three times, three fold, thrice, in the third place, thirdly, trebly.