The word 'sung' originates from the Old English verb 'singan', meaning "to chant, sing, recite, or celebrate in song." This verb is of Germanic origin, related to Dutch 'zingen' and German 'singen'. It is derived from the Proto-Germanic sengwan, which itself may have roots in the Proto-Indo-European sengwh-, meaning "to sing, make an incantation." The past participle form 'sung' developed through regular sound changes from the Old English 'gesungen'. Its journey reflects the standard Germanic pattern of strong verb conjugation, where the vowel changes (sing-sang-sung) to indicate tense, a feature preserved from its ancient ancestry.

The word 'sung' is an inflected form of the verb 'sing'. It is not productively composed of multiple morphemes in modern English. Its core is the Germanic root 'sing-'.