Definition of ownty-downty in English:

ownty-downty

Pronunciation /ˌəʊntɪˈdəʊnti/

adjective

(also ownty-donty)
informal US
  • Own pron.

Origin

Early 19th century; earliest use found in David Humphreys (1752–1818). Reduplication of own with variation of the initial consonant and suffixation, in imitation of childish speech.