Hindi/Gender

Nouns in Hindi will fall into one of two genders: masculine or feminine. Many masculine nouns end in the vowel आ or ा and many feminine nouns end in the long vowel ई or ी , but there are exceptions to this rule. Usually, feminine words borrowed from Sanskrit end in the vowel आ or ा (for example, भाषा meaning "language," is a feminine noun) and the masculine words borrowed from Sanskrit end with the vowel अ but since the last vowel of all the words in Hindi are silent if they end in an अ, so all such borrowed words end in a consonant in Hindi (for example, the masculine word कर्म which is pronounced as "karma" in Sanskrit but pronounced "karm" in Hindi; the final अ vowel is silent). 
There also are many loan words from languages like Persian, Turkish, Arabic, Portuguese, English into Hindi and very often there is no predictable rule or method to determine the gender. What gender sounds better with which word is how the genders are usually assigned for the loanwords. For example, the Arabic loan word आदमी, meaning "man," is a masculine noun but yet ends with an ी vowel.
List of Some Loanwords from Different Languages and their Genders.
The languages out of which most loanwords are present in Hindi are Arabic, Persian, Portuguese and English.
Arabic.
There is no particular logic that can be established here to predict the gender of the words. 
Persian.
It could be noted here (with a few exceptions) that many masculine words end in आ or ा but nothing conclusive can be said about the feminine words. It can be said that most words that end with िश are feminine.
Suffixes.
There are some borrowed suffixes from Persian to Hindi which when used with a word the gender of the word could be determined with surety. 
-दार.
The Persian suffix word -दार, when added at the end of nouns, conveys the idea of possession, holding, bearing or having. The combined word either acts as a noun or an adjective. For examples, some words which form nouns after adding -दार are mentioned below. The addition of the suffix -दार makes the word a gender flexible word which means that the same word could be used to describe both feminine and masculine nouns. The gender of the following words would be assumed to be same as the subject or the object it describes.
-दारी.
The suffix -दार when changed to -दारी changes the meaning of the suffix which often is equivalent to Engish's -tion, -ship or -ness or -ing suffixes. These formed nouns are always guaranteed to be feminine.
English.
The most amount of loanwords in Hindi is from English. A huge amount of English words are very often used as the default word in Hindi. The English words although not having genders when used in the English language but in Hindi just as the rest of the words, are assigned either the masculine or the feminine gender. You will soon see that it is often much easier to identify which English words are feminine words than masculine in Hindi, but luckily most English words' genders which cannot usually be predicted will be masculine. A few examples of loanwords are mentioned below:
An approximate logic which can be established is: most words which end in or have in their second-last position these following vowels: ई or ी or इ or ि, are interpreted as feminine words.
Suffixes.
There are certain suffixes in English which when used in words would make the English words be interpreted as feminine in Hindi.
-ity.
Al the English words ending -ity are always interpreted as feminine in Hindi.
-ing.
Almost all English gerund nouns formed by adding the continuous tense suffix -ing to them could be interpreted as both masculine and feminine words depending on the context. Usually, when the word follows after a genitive case pronoun it is used as a feminine word but when it is without a pronoun preceding it (or maybe the pronoun is after the word ending in -ing), it is almost always interpreted as masculine. This phenomenon of "confused genders" happens not just for words of foreign origin but often also with pure Hindi feminine words in certain contexts. It depends on the position of words in the sentence (word-order) and also on the nuance of the sentence (Read the reference attached to know more about this phenomenon). 
Example: 
-tion.
All the English nouns which are formed by the addition of the suffix -tion or just the -tion sound are almost always considered masculine in Hindi. 
Portuguese.
Some very commonly used loanwords from Portuguese are as follows: