What term is used to describe a collection of many cells?

The term "tissues" is used to describe a collection of many cells that work together to perform a specific function. In biological contexts, tissues are categorized based on their structure and function into four main types: epithelial, connective, muscle, and nervous tissue. Each type serves a distinct purpose and is composed of similar cells that collaborate to facilitate various physiological processes.

While "organs" refers to a group of tissues that work together to perform complex functions within an organism, and "systems" refers to groups of organs that cooperate to carry out broader biological tasks, neither term specifically denotes just a collection of cells. The term "clusters" is less formal and not commonly used in the biological sciences to describe organized collections of cells in the same systematic way that "tissues" are defined. Therefore, the use of "tissues" is the most accurate term in this context.