each; every; at intervals of
Indicates that something happens for each unit or at regular intervals.
This ごとに means 'each' or 'every' and stresses that something occurs repeatedly for each item or interval. It attaches to a noun (like 人 or 日) or to a verb in its dictionary form. For example, 人ごとに means 'for each person', and 日ごとに means 'day by day' or 'every day' (emphasizing change or repetition). When attached to a verb, like 会うごとに, it means 'each time we meet' or 'every time we meet'.
You can also use it with intervals like 一時間ごとに, meaning 'every hour'. Note that ごとに is more formal and written-oriented than たびに, but both can mean 'each time'. However, ごとに often emphasizes regularity or division into units, while たびに emphasizes 'every occasion'.
Be careful: the same spelling ごと (without に) can mean 'together with' or 'including' (as in ごとく? Actually, ごと is used in ごとし meaning 'like'). Also, there is a different grammar point ごと (like あたかも...ごとく) meaning 'like/as if', but that is literary. In this entry, we focus only on ごとに meaning 'each/every'.