From their web page, his winning words were:
1 sanguine sanguine
2 (written round) (advanced to round three)
3 insalubrious insalubrious
4 Veracruzano Veracruzano
5 marmoraceous marmoraceous
6 mistassini mistassini
7 solfeggio solfeggio
8 piezochemistry piezochemistry
9 voussoir voussoir
10 halogeton halogeton
11 dipnoous dipnoous
12 gadarene gadorene
13 peirastic peirastic
14 rhathymia rhathymia
15 pococurante pococurante

5< Cree mista-assini, lit., the great stone lake6 lake in SC Quebec, Canada: 840 sq. mi. (2,176 sq. km)

5Fr < OFr volsoir, curvature of a vault < VL *volsorium < *volsus, for L volutus, pp. of volvere, to roll: see WALK6 Archit. any of the wedge-shaped stones of which an arch or vault is built: see ARCH1, illus.

I now remember having seen this word a couple months ago.

5ModL < HALO3 + Gr geitbn, neighbor6 a poisonous Asiatic weed (Halogeton glomeratus) of the goosefoot family, with fleshy, cylindrical leaves and minute, papery flowers, becoming widespread in the W U.S.

a. having both lungs and gills. dipnoan, n. such fish; lungfish.

... Aristotle's Account of the Socratic Elenchus " focuses on the type of dialectic called "peirastic" which Bolton shows is based upon Socratic practice.

rhathymia personality factor leading to optimism and cheerfulness