Patchy describes something that exists in some spots but not others, creating an uneven or incomplete pattern. When snow cover is patchy, you see white patches here and there with bare ground showing through. When your knowledge of a subject is patchy, you understand some parts well but have gaps in others.

The word suggests inconsistency or irregularity. A lawn might have patchy grass, with thick green areas next to thin, brown spots. Fog can be patchy, thick in some places and clear in others. A student's performance might be patchy, excelling at some assignments while struggling with others.

Patchy often indicates something incomplete or not quite right. If your internet connection is patchy, it works sometimes and fails at other times. If someone's memory of an event is patchy, they remember certain details clearly but can't recall others at all. A patchwork quilt, made from different fabric pieces sewn together, captures this same idea of things existing in irregular sections rather than as one smooth, continuous whole.