"tuition" is uncountable, yes? So "tuitions", certainly when referring to individual lessons, is incorrect?

Question

Can anyone help me find a reference to support this?

Answer 1

Tuition means "payment for instruction" or "the charge made for it". "Payment" refers to "an amount of money to be paid". Both words ("payment" and "tuition") are classified as uncountable nouns.

According to grammar, an "uncount noun" "cannot be counted directly", "does not have a plural noun"; "is not used with numbers" (Willis, 1995:12). But, as Richards et al. point out, an uncountable noun (= mass noun) "does not USUALLY occur in the plural" (1987: 66). The examples provided are "education, homework and harm" (emphasis mine).

As far as grammatical rules, some of them are quite clear and unquestionable. For example, "countable nouns have both singular and plural forms" (Richards et al.: idem) and "uncountable nouns do not have a plural form" (Willis: 12).

However, speakers, when faced with tough decisions as "tuition or tuitions", sometimes have to bend the rules. In turn, grammarians must acknowledge that (a process which may take years, even decades).

Long story short, whenever speakers have to decide between one form or the other, analogy is the answer. By analogy, one can come up with a plausible explanation. Take "coffee" and "beer", for example. Both are "uncountables" ("Do you want some coffee/beer?"), which are also used as "countables" ("Two coffees/beers, please"). Therefore, by analogy, we may say that depending on the context, one may use "tuition" or "tuitions":

(A) If you are a resident, do you have to pay tuition?
(B)These are the two tuitions I told you about.

As the examples above show, in (A), "tuition" means "a fee"; in (B), it refers to the "two tuition forms" the speaker has referred to previously.

Answer 2

tuition is already plural. tuitions is already incorrect by definition.

Oxford Dictionary would be your best reference as they will not include tuitions as the plural.