GayanšgwadÕs (Phyllis Eileen Wms. Bardeau, Deer Clan) English-Onšndowa'ga:' (Seneca) dictionary is a cultural and linguistic treasure trove. Eileen, a fluent first language speaker and elder, speaks and records the Onšndowa'ga:' language as she learned it from her grandmother, several generations ago before the building of the Kinzua Dam in the 1960s. This tragic treaty violation accelerated language loss by breaking up almost two century old communities at Ohi:yonšÕ (Allegany Territory residents, Lit. people of the Ohi:yo_) of the Onšndowa'ga:'. She devoted her life to the preservation of the Onšndowa'ga:' language. Phyllis created Definitive Seneca: ItÕs In The Word as a permanent tool to study culture through language. Gayanšgwad has taught the language in the community, for the Seneca Nation, and at the University level. This publication should be in every library for students of the OnšndowaÕga:Õ Gaw‘:nš_ (Language of the People of the Great Hills).