The heraldic term for a partition line or charge in which one or more curves interrupt a normally straight line or lines, is termed nowy. (And now you knowy.)
Like many heraldic terms, 'nowy' is from a French word, noué, which in turn is from the Latin nodatus, meaning 'knotted', as in the knot of a tree. (The word 'node' has the same Latin root.)
In addition to the bulge seen in the cross on this page, a nowy is also the term for a sine wave, either concave or convex.
Another name for this convex shape is "Flaunch", and when the curve is concave it may be called (confusingly similar) Flanch.
See also the Glory Cross.