Umteen is a colloquialism used to describe an indefinite or very large number of something. There are numerous synonyms that can be used interchangeably like zillions, gazillions, jillions, squillions, and bajillions. These words are often used by people who want to exaggerate the quantity of something in a humorous or playful way. The use of these words may also depend on the situation, context, and the formality of the gathering. While they are not formal or precise, they do convey the intended message of an inconceivably large number. Overall, the use of these synonyms can add color to conversations and make them livelier.