We found 4 dictionaries that define the word like water off a ducks back:

General (3 matching dictionaries)

1. like water off a duck's back: Merriam-Webster
2. like water off a duck's back, like water off a duck's back: Collins English Dictionary
3. like water off a duck's back: Wiktionary

Miscellaneous (1 matching dictionary)

4. like water off a duck's back: Idioms

▸ Words similar to like water off a ducks back ▸ Usage examples for like water off a ducks back ▸ Idioms related to like water off a ducks back ▸ Wikipedia articles (New!) ▸ Words that often appear near like water off a ducks back ▸ Rhymes of like water off a ducks back ▸ Invented words related to like water off a ducks back