singsong vs intoned

singsong is a noun but intoned is not a noun.

Word	Noun	Adjective	Verb	Adverb
singsong	Yes	Yes	Yes	No
intoned	No	Yes	No	No

As adjectives, singsong and intoned are synonyms defined as:

singsong and intoned: uttered in a monotonous cadence or rhythm as in chanting

Other synonyms of singsong include chantlike.

singsong (noun)	intoned (noun)
informal group singing of popular songs
a regular and monotonous rising and falling intonation

singsong (adjective)	intoned (adjective)
uttered in a monotonous cadence or rhythm as in chanting	uttered in a monotonous cadence or rhythm as in chanting

singsong (verb)	intoned (verb)
speak, chant, or declaim in a singsong
move as if accompanied by a singsong