Rub-a-dub means the rhythmic, repetitive sound of a drum being beaten. It is an imitative expression: the words are intended to evoke the sound of drumming.
How “rub-a-dub” is used
The expression can describe:
- A drumbeat or other drum-like rhythmic sound
- A repeated, energetic noise associated with drumming
- In some contexts, a figurative sense of agitation or lively commotion
For example, a sentence describing a drummer might refer to the steady “rub-a-dub” of the drums. The exact sense depends on the surrounding context, especially when the term is used figuratively rather than to describe an actual drum.
Is it “rub-a-dub” or “rub-a-dub-dub”?
Rub-a-dub-dub is a related extended form. It is also associated with a drumlike sound and is known as the opening phrase of the traditional nursery rhyme commonly beginning “Rub-a-dub-dub.”
That related form should not automatically be treated as interchangeable with every use of rub-a-dub. The available dictionary evidence supports the connection, but it does not establish all possible variants, usage frequencies, or a definitive register for either expression.
In short
Rub-a-dub is a sound-imitating expression for the rhythmic sound of a beaten drum. Rub-a-dub-dub is a related form that is also associated with drumming and with the opening of a traditional nursery rhyme.