arbelos
English
Etymology
From (deprecated template usage) [etyl] Ancient Greek ἄρβηλος (árbēlos) or ἄρβυλος (árbulos), literally "shoemaker's knife".
Noun
![](http://upload.wikimedia.org/wikipedia/commons/thumb/6/68/Arbelos_diagram_with_points_marked.svg/200px-Arbelos_diagram_with_points_marked.svg.png)
arbelos
- (geometry) A plane region bounded by a semicircle of diameter 1, connected to semicircles of diameters r and (1 − r), all oriented the same way and sharing a common baseline.