Term for words like "Hanky-Panky" [duplicate]

hanky-panky is an example of rhyming reduplication

zig-zag is an example of ablaut reduplication

https://en.m.wiktionary.org/wiki/reduplication

I believe the word you're looking for is reduplication.

From Wikipedia:

Reduplication in linguistics is a morphological process in which the root or stem of a word (or part of it) or even the whole word is repeated exactly or with a slight change.

Wiktionary gives specific types:

• Exact type: acute-null accents; baby-talk-like
  • bye-bye, choo-choo, night night, no-no, pee-pee, poo-poo, etc.
• Ablaut type: acute-grave accents, high-low vowels, front-back vowels.
  
  • bric-a-brac, chit-chat, criss-cross, kitty-cat, knick-knack, jibber-jabber, splish-splash, zig-zag, sing-song, etc.
• Rhymed type: acute-acute accents, varied initials.
  • claptrap, hokey-pokey, honey bunny, razzle-dazzle, slim jim, super-duper, teeny-weeny, wingding, etc.