The antonyms for "fanning out" are words and phrases that denote a decrease in expansion or spreading. These include gathering, converging, centralizing, consolidating, clustering, and contracting. When one gathers, things come together into a group or pile. Converging denotes things coming together from different directions to meet at a focal point. Centralizing and consolidating denote the combining of different parts into a single unit. Clustering denotes grouping together of things that are similar while contracting means reducing in size or amount. All these antonyms describe constricted or reduced movement, unlike "fanning out," which denotes a spread or an increase in space or reach.