Sentence:  3Lang's "Algebra" [Lan02, p. 759] supports the general consensus that this was not intended as an epithet:/  In the forties and fifties (mostly in the works of Cartan, Eilenberg, MacLane, and Steenrod, see [CE56]), it was realized that there was a systematic way of developing certain relations of linear algebra, depending only on fairly general constructions which were mostly arrow-theoretic, and were affectionately called <WSD>abstract nonsense</WSD> by Steenrod. 
Meaning of the word marked with <WSD> tags:  Details which involve diagram chasing.