Multiplet Definition:

In 1H NMR spectroscopy, a signal whose multiplicity requires a more detailed analysis.

Multiplet Explained:

When an NMR signal split but is very difficult to study. In the 1H-NMR spectrum of 2-ethylphenol, the CH3 signal is a triplet, the CH2 signal is a quartet, the OH signal is a singlet, and the benzene ring protons signal is a multiplet.