Amphibrachic meter is a rhythmic pattern made of three-syllable feet in which the middle syllable is stressed and the first and third are unstressed: da-DUM-da. It is more natural in languages with flexible stress patterns than in English, where it appears less often and is usually used for a deliberate, sing-song, or rolling effect.
Because English verse is usually based on stress rather than syllable length, the term is often used for accentual-syllabic patterns that sound like amphibrachs rather than for classical quantity-based meter.
Example
The moonlit stream was silver-ing bright,
while willow leaves were whispering light.