fuけるkerufuけるkeru
1.

To indicate the passage of time, particularly when night progresses towards midnight, suggesting a deepening of darkness and stillness as hours go by.

2.

To describe the transition of a specific season as it reaches its peak, reflecting the idea of time passing in relation to seasonal changes.

3.

To denote a state in which living beings, such as animals, become sexually active during their mating season, highlighting a natural progression in behavior as time advances.

4.

To imply an aging appearance, often referring to someone who looks older than their actual age, suggesting a deterioration or change related to time.

5.

To express the idea of an object or substance becoming aged or altered, indicating a transformation that occurs over time as it is subjected to environmental influences.

Example:

だいぶ夜もふけました。もうおいとませねばなりません。