The origins of the concept began with certain interpretations of Mendelian inheritance and the theories of August Weismann. The word "eugenics" is derived from the Greek word "eu" ("good" or "well") and the suffix "-genēs" ("born"); Galton intended it to replace the word "stirpiculture", which he had used previously but which had come to be mocked due to its perceived sexual overtones. Galton defined eugenics as "the study of all agencies under human control which can improve or impair the racial quality of future generations".