Sentence:  Now consider the two <WSD>septics</WSD> C = U7<sub>i=1</sub>C<sub>i</sub>, D = U7<sub>i=1</sub>D<sub>i</sub> and note that for i = 1,2,3,4,5,6 the lines C<sub>i</sub> and D<sub>i</sub> are parallel, so that the intersection of two septics S' consists of 66sic + 6 + 1 = 43 points and it is the singular set of a foliation of degree 6. 
Meaning of the word marked with <WSD> tags:  A mathematical object (function, curve, surface, etc.) of degree seven.