Indefinite adjectives are adjectives which do not specify a specific quantity.
The most common indefinite adjective in English is perhaps “some”: “I want to drink some water”, “Some people are coming here tonight”, etc.
The indefinite adjectives in Hindi are कोई and कुछ. They have the same form as the indefinite pronouns in Hindi.
An important property of nouns is “countability”. Typically, countable nouns are nouns that refer to items that can be enumerated, although this is not always true. Countability is a grammatical property, not a semantic property. A countable noun is a noun that can be modified by numerals, has singular and plural forms, and can be modified by certain quantifiers, such as “each”, etc.
Countability in English
The phenomenon of countability can be observed in English via the words “much” and “many”.
“We don’t have much furniture” – You would not say “We don’t have many furnitures”
“We don’t have many books” – You would not say “We don’t have much books”
We can enumerate books, and the word “book” has a plural form – one book, two books, three books, etc. It is therefore countable.
Furniture is an uncountable “mass noun”. It does not have a plural form (“furnitures”), and cannot be enumerated (“one furniture”, “two furnitures”). It refers to items collectively. Often in English, uncountable nouns are used with a countable noun and the preposition “of” – “one piece of furniture”, “two pieces of furniture”, etc.
Countability in Hindi
कोई is used with countable nouns.
कोई आदमी उस कमरे में बैठा हुआ है – “Some man is seated in that room”
कोई किताब वहाँ पड़ी हुई थी – “Some/a book was lying there”
कुछ is used with uncountable nouns.
कुछ पानी चाहिए? – “Do you want some water?”
कुछ पैसा ले लो – “Take some money”; Note that although the referent of the word पैसा (“money”) is indeed countable, it is nonetheless grammatically uncountable, since it refers to money as a composite whole, and the constituent parts are irrelevant.
कुछ दाल खा लो न – “Eat some lentils, won’t you?”; Again, although lentils are enumerable, each individual lentil is irrelevant; दाल simply refers to the food as a whole, and is grammatically uncountable.
Thankfully, these two examples correspond nicely to English – we say “I don’t have much money” and “I didn’t each much daal”, not “I don’t have many monies” or “I didn’t eat many daals”.
The singular oblique form of कोई is किसी.
किसी आदमी से बात कर रहा था – “He was talking with some man”.
The plural form of कोई is कुछ in both the direct and oblique cases.
कुछ विदेशी हिंदी बोलते हैं – “Some foreigners speak Hindi”
कुछ लड़के के साथ खेल रहा है – “He is playing with some boys”
The adjective कई (“many”) may sometimes be used like a plural form of कोई.
कई लड़कियां से बात कर रही थी – “She was speaking with several girls”
Hindi has no direct equivalent of the English indefinite article “a”, although the word कोई often functions similarly (as does एक “one”):
कोई लड़की दरवाजे के पास बैठी हुई थी – “A girl was sitting near the door”