multiplet

Short definition from Wiktionary

Noun

1. 1
   A group of many parts, particularly: A spectral line that has multiple components.
2. 2
   A group of many parts, particularly: A compound peak produced in several forms of spectroscopy.
3. 3
   A group of many parts, particularly: Any of several groupings of subatomic particles that share most properties, but have different charges.