The phrase "fell lot" refers to a significant or substantial amount, and it can be replaced by various synonymous terms. For instance, the expression "a great deal" means a large amount, and it implies an abundance or a plentiful quantity. Additionally, the phrase "a considerable amount" refers to a significant or noteworthy quantity of something. "A substantial amount" is another synonym for "fell lot" that connotes a significant or meaningful degree. Alternatively, "a hefty amount" suggests a weighty or substantial quantity of something. These synonyms can be used interchangeably with "fell lot" to convey the same meaning of a significant or sizable amount.