IPA: /ˈsɪŋsɔːŋi/
KK: /sɪŋˈsɔŋi/
Having a rhythmic, musical quality, often in a cheerful or playful manner.
The children sang in a singsongy voice during the game.
Singsongy → It is formed from "sing" (from Old English "singan", meaning to produce musical sounds with the voice) and "-song" (meaning a musical composition) combined with the suffix "-y" (meaning characterized by). The word "singsongy" describes a style that is characterized by a musical or rhythmic quality, often in a playful or repetitive manner.
Think of the act of 'singing' and 'songs' that are 'characterized by' a playful rhythm — that's what 'singsongy' means.
No commonly confused words.