This is the 1113th most frequent French word.
cesse
"Cesse" means "cease" or "stop" in English.
In this sentence, 'cesse' is used as part of the phrase 'ne cesse de' which means 'does not stop'. It conveys the continual action of singing.
Elle ne cesse de chanter toute la journée.
She does not stop singing all day long.
Here, 'cesse' serves as the verb form expressing the stoppage of an action (to cease). It is in the subjunctive mood due to the demand.
Nous demandons qu'il cesse ses critiques incessantes.
We ask that he cease his incessant criticisms.
In this example, 'cesse' illustrates the action coming to an end, referring to the noise stopping.