Webster's Revised Unabridged Dictionary · 1913

Singsong

Singsong , noun

1.
Bad singing or poetry.
2.
A drawling or monotonous tone, as of a badly executed song.

Singsong , adjective

Drawling; monotonous; having a monotonous cadence.

Singsong , intransitive verb

To write poor poetry. [Rare] — Tennyson