adverb, adverb taking the 'to' particle
gradually; slowly but steadily; little by little
Mimetic adverb describing a slow, steady, often imperceptible progression. Often used with verbs of change, approach, or encroachment.
See also: じわり
水位がじわりじわりと上がっている。
The water level is rising little by little.
敵がじわりじわりと迫ってきた。
The enemy closed in slowly but steadily.