What is the meaning of Quadruplet?

A set of four, particularly

A tuplet of four notes.

A sequence of four elements.

One of a group of four, particularly one of four babies born from the same mother during the same birth.

A cycle for carrying four riders, arranged so that all the riders can assist in the propulsion.

quadruplet (sequence of 4 elements)

third-person singular present active subjunctive of quadruplō

Source: wiktionary.org