Definition of nocturnality in US English:

nocturnality

noun

Zoology
  • Nocturnal behaviour; the condition of being nocturnal.

Origin

1930s; earliest use found in American Journal of Ophthalmology. From nocturnal + -ity; compare -ality.

Pronunciation

nocturnality

/ˌnɒktəːˈnalɪti/