Strange Loop
A cyclic structure that goes through several levels in a hierarchical system, and arises when, by moving only upwards or downwards through the system, one finds oneself back where one started.
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Origin
Introduced by cognitive scientist Douglas Hofstadter in his 1979 Pulitzer Prize–winning Gödel, Escher, Bach, which wove together the self-referential structures in Gödel's incompleteness theorems, Escher's impossible drawings, and Bach's fugues. Hofstadter revisited the idea in his 2007 work I Am a Strange Loop.
Updated February 22, 2026