Category theory & homological algebra
Objects, morphisms, and composition — the structural patterns common to all of mathematics.
Founded: 1945 — Eilenberg & Mac Lane's General Theory of Natural Equivalences
The claim
attributed to Norman Steenrod, 1945: “Abstract nonsense” — possibly an affectionate in-joke more than a hostile dismissal.
Source: Attribution via Rotman (Bull. AMS 33:4, 1996) and McLarty (Br. J. Philos. Sci. 41, 1990); no primary quote from Steenrod himself has surfaced.
The label was popular among the field's own early practitioners, and McLarty and Rotman describe it as a joke or self-deprecating. It is counted as a named dismissal with that caveat.
What happened
Monads in functional programming (1989) — Moggi applies category-theoretic monads to programming-language semantics; standardized as Haskell's I/O mechanism by 1996.
44 years — founding (1945) to Moggi's monads (1989)
Verdict: Named dismissal, later applied.
Confidence: medium.