سلامٌ عليكم مجددًا Nice question, in fact in Arabic we even describe things with feminine and masculine expressions, so we don't have "it" literally in Arabic. Thus, those expressions could be used with people and things, but when we use them with people we mean to express our feelings toward those people, it's a metaphorical expression. So if I say to may mum, for instance, that "You are expensive for me my mum" "أنتِ غاليةٌ عليّ يا أمي" that means I said I love her too much, that she means a lot for me. The same thing with friends or others. But when we use it with things, that could mean either this thing is expensive in terms of its price, or I love this thing so much. The other thing, that grammer which is applied with "غالي" must be applied for "غوالي", so we remove the letter "ي" from the end of the word, it would be "أشخاصٌ غَوَالٍ" or with another form "أشخاصٌ غَالونَ", this form's not important, just for the sake of knowledge :} . I hope it's clear now, anything else? :)

و عليكم السلام !جزاك لله Yes, my fault for #3 - I meant to say وقع but سقط works too! So are you saying for the plurals غالون غاليات and غوالي - these would only be used for people? Like رجال، نساء or أشخاص? Or can you use them for things أشياء too? Just saying, because "people" aren't usually seen as "expensive", mainly things... so not even sure how often those plurals are used! Also would it be أشخاصٌ غواليْ or أشخاصٌ غواليٌ? Thanks again :-)

سلامٌ عليكم مُعِزّ. First of all, your examples are correct, except the third one, it's grammatically correct but it has no logical meaning, I think you meant to say, "سقط الشيء الغالي" instead of "وقف", didn't you? Secondly, in fact the word "غال" is originally "غالي" (you seem like you know that :)) therefore you can make some plural forms of it. You can make a plural masculine form "غالون", a feminine plural form "غاليات" as you mentioned or a plural form that fits both "غوالي", it's up to you, but you can just forget all these things and use "غال" for singular male, "غالية" for plural and singular female, and "غوالي" for both plural male and female. Hope to be understandable