reptation
/rɛpˈteɪʃn/noun
Chemistry. The snake-like movement of a polymer chain in a tangled state, when it is constrained within a topological ‘tube’ by surrounding molecules.
Origin
Mid 19th century (in an earlier sense). From French reptation action of creeping or crawling, especially in the manner of a snake and its etymon classical Latin reptātiōn-, reptātiō action of crawling (Quintilian) from reptāt-, past participial stem of reptāre to creep + -iō.