Polysyndeton is the deliberate use of many conjunctions, such as and, or, or but, close together in a line or passage. Poets use it to slow the pace, build rhythm, and make a list or sequence feel fuller, more urgent, or more intense than ordinary speech.
Example
The rain came and the wind came and the night came down,
and the doors shook and the windows rattled and the lights went out.
Related Definitions
[n] using several conjunctions in close succession, especially where some might be omitted (as in `he ran and jumped and laughed for joy')