1 : a decoration on a surface made by pressing small pieces of colored glass or stone into a soft material that then hardens to make pictures or patterns [count] ▪ a church decorated with old mosaics [noncount] ▪ a picture done in mosaic — often used before another noun ▪ a mosaic floor ▪ mosaic glass/tiles 2 [count] : something made up of different things that together form a pattern — usually singular ▪ a complex mosaic of islands ▪ the country's ethnic/political/religious/social mosaic








