The change is often too slow to notice immediately, but becomes obvious over time.

Gradual Increase

Often used to describe negative developments or the onset of problems.

Negative Tendency

The process described is not direct or forceful, but subtle and possibly unnoticed at first.

Moving in a way that avoids being seen or heard; used for people or animals.

Describes a method of entering that is intended to be unnoticed, often for surprise.

When time seems to move slowly, particularly during waiting or anticipation.

Time or process moves so slowly it's hard to perceive any change without reflection.