Meanwhile I count eight occurrences of "abut" and "abutment" in the (36 kilobyte!) main Wikipedia article on spectral sequences (there are a dozen separate much shorter articles on particular spectral sequences, along with a 15 kB article on derived categories). On the other hand the algebra and geometry articles of the 1987 Britannica Macropaedia both prefer the term "limit" for what a spectral sequence converges to, in respectively Peter Hilton's contribution "Other aspects of homological algebra" to the algebra article, and the geometry article's section on algebraic topology. Since Wikipedia seems to be trumping Britannica these days, and no one here has objected to established usage in mathematics trumping linguistic suitability, the precise distance of "abutment" from the optimal English cognate for "aboutissement" would appear to be academic, an epithet reflecting the outside world's perception that raising moot points is in our job description. Vaughan
Thanks to Eduardo D and Vaughan P and Michel H for their misgivings, which encouraged me to compose the above, despite the assurances of Jim S that the 'abut*' usage is by now well entrenched.
Fred