Serpentine verse is a chained poetic pattern in which one line, stanza, or sentence picks up a word from the end of the previous one and carries it forward. The repeated word links the lines together in a winding, back-and-forth movement, which is where the name comes from.
Because the term is used inconsistently, it is sometimes confused with other repeating or circular verse patterns.
Example
The river turns to mirror sky
Sky loosens into evening blue
Blue drifts across the sleeping hill
Hill folds into the dark below