reduplicative (n. & adj.) (A compound word) having two identical or
very similar parts, often rhyming. (Sometimes called iterative.)
Most reduplicatives are fairly informal, e.g.
goody-goody (M19) hugger-mugger (E16)
happy-clappy (L20) wishy-washy (E18)
Source: "reduplicative" in The Oxford Dictionary of English Grammar.
Sylvia Chalker and Edmund Weiner. Oxford University Press, 1998.