‘一团’ (yī tuán) is a measure phrase used for uncountable or amorphous substances that form a compact, rounded mass—like smoke, fog, yarn, dough, or even a group of small animals huddled together. The first character ‘一’ means ‘one’, serving as the numeral, while ‘团’ literally means ‘ball’, ‘lump’, or ‘cluster’, indicating shape and cohesion. Together, they emphasize visual unity and physical boundedness rather than precise quantity.

This phrase is commonly used in descriptive, everyday speech and writing, especially when evoking imagery—such as ‘a fluffy mass of kittens’ or ‘a swirling mass of mist’. It often carries a neutral or slightly poetic tone and works with nouns that are naturally soft, flexible, or loosely aggregated. Unlike countable classifiers like ‘个’ or ‘只’, ‘团’ highlights shape and collective behavior, not individual units.