The phrase "small indefinite amount" refers to a quantity of something that is imprecise and difficult to measure. There are several synonyms for this phrase, including "trace amount," "scant quantity," "tiny portion," and "modicum." Other possible alternatives might include "minute fraction," "barely noticeable quantity," or "miniscule amount." The choice of synonym may depend on the context in which the phrase is being used, as well as the desired tone and emphasis. Whether describing a chemical compound, food ingredient, or personal finance issue, these synonyms can help convey a sense of vagueness or ambiguity.