It can be a mass noun like most agricultural products
קטפתי אבוקדו כל היום
But it's usually a regular singular noun. It is a loan word, and one that does not fit Hebrew morphology well. In speech I might say "a-vo-CA-do-im", and it possible to write it:
This is correct (It's in the dictionary), but it looks weird. In writing I would try to avoid it either by using it as a mass noun as above, or by rephrasing the sentence to talk about fruits or kilos or pieces. But there's nothing wrong with using the plural form.
Thanks! I never really thought about it before, but I'm doing some revision and it occurred to me I really wasn't sure how you'd do it, because it doesn't, as you say, fit morphology well. It's roughly what I would've guessed in speech, but in writing I would've missed the א which I think probably would make it look even weirder 8-o
(I have noticed that a lot of borrowed words look odd to me in Hebrew - a teacher told me, actually, that it's not uncommon for English speakers to have more difficulty reading words like אוניברסיטה or אוטובוס, which should be easy because they are familiar in sound, than native Hebrew words.
I know I am more likely to stumble on words that in theory I should know than on words that I don't know/instantly understand but that fit better into my understanding of how Hebrew works ;-p Hebrew is the first language I've ever learned where reading is one of the harder skills, not the relatively easy one LOL)
My big two-volume 1965 dictionary by Alcalay gives the plural as avokadim. אבוקדים Since it's a borrowed word, and a final letter o might sound like a masculine singular, it would make sense to delete it when you're adding the Hebrew plural ending. As to the question of whether it's a mass noun or not, it can be either. E.g , if "I want avocado in my salad," that's using it as a mass noun, but if I'm shopping, "Do I want to buy three avocados today or just two?" is the usage.
With all respect to AlKalay, in 1965 avocados were an exotic fruit that was not very well known in Israel, so they could invent a plural form.
In the 1980s it became very popular, and as it turned out, everyone used אבוקדואים, which is a bit unusual, because it is a longer form. Nevertheless, this is what people say, and I am pretty sure that dictionaries followed along.
In the sentence "does she like avocado", is the word "does" necessary?
You can say "She likes avocado?", just as you can say "היא אוהבת אבוקדו?"
That's taking a statement and adding a question mark at the end to make it a question about the veracity of the statement. This is a perfectly valid construction in Spanish. In both Hebrew and English, it's colloquial.
In English, most people who speak correctly will use the "does". In Hebrew, I would use האם in writing, but I often skip it in speech.