"Без цитрини." is also frequently used in Ukrainian. 'Цитрина' ('tsytryna') сomes from the word 'citrus'.
"Без цитрини." is not correct. There are few citrus fruit. The majority of Ukrainians do not understand what you mean "Без цитрини."
Цитрина means lemon in a certain dialect (Галицький діалект). But we don't accept dialectal words here, otherwise we'd have to add ten words for "lemon", and probably for each word :) And because it's more useful to teach the standard most mainstream dialect. But, it's fun to learn dialectal words in the comments! ^^
Aren't lemons countable objects, so that we should use "лимона"?
In genitive masculine nouns end in either а or у, it depends on the type of that noun
лимона is the correct form here indeed.
And you are right, one could probably say that countable nouns usually take -а/-я, while most uncountable nouns take -у/-ю. This definition would be helpful but it would also have a number of exceptions (like names of cities which are uncountable but take -а/-я). I think I'm going to make a detailed post about that :)
Дуже вдячний вам! I thought it was "лимона" exactly because the text in this lesson said that countable or concrete objects take endings -а/-я in the Genitive case. I would really appreciate if you could make a detailed post :D!
Since Russian genitive nouns don't end in -у, I'm confused about the Ukrainian rule. So the mass nouns with masculine gender take -у, while countable masculine nouns take the -а ending? For example немає сиру? Немає лимона? What about хліб? Немає хлібу?
Exercises in this lesson keep stating хліба, and Vinnfred's comment above states that the proper ending а/я or у/ю has nothing to do with countable or uncountable nouns. My understanding to date is that a lot of Ukrainian grammar revolves around what sounds good/better. Maybe that's the case here; хліба sounds better to me than хлібу.
Ukrainian is between Polish and Russian. The -y is similar to Polish, and the -a is similar to Russian.
This confusion is for masculine nouns with no vowel at the end in Genitive case.
The most general rule is, if it's an object, if you can touch it, see it, it's а. If it's abstract, or uncountable, or a mass noun, it's у.
But, there are exceptions. E.g. math terms all have а (косинуса, синуса) even though they're abstract.