Disclaimer: I'm as confused as everyone else, so not sure this is 100% correct, but I think the base word for woman is المرأة, but it gets pronounced slightly differently whether it's nominative, accusative, genitive. I derive this info from Lesson 3 of A.S. Tritton's Arabic (Teach Yourself Books) p. 33. The grammatical gender of the word affects the case. The letter t makes sense for feminine words because that's the same for Semitic languages in general. The tu(n) ending is because it's nominative, similar to "garden" or paradise in the nominative being jannatu(n), but in accusative, jannata(n), and genitive jannati(n). (That vocab for garden comes from Tritton, and it may be more Quranic than the various words for garden today. Also, for Tritton's examples, the definite article results in no final nun, hence the nun is in parentheses.) But, yes, these endings are not written in the sentence we are given! See the responses of RajasDaith & Fix & marlztone below, who know Arabic.
@ideo - "un" suffix indicates that the word is indefinite and in nominative case (e.g. subject of a sentence). "an" suffix indicates indefinite in accusative case (e.g. direct object of a transitive verb). "in" suffix indicates indefinite in genitive case (showing possession). The above examples are indefinite nominatives hence end in "un" suffixes.
In Arabic, there is a grammatical situation called "Nunation" when a noun or adjective is indefinite. Nunation marks words that are in definite. This is sort of like how we have "a" and "an" in English. I'll explain this as best as I can.
Nouns are definite if they are: 1. A person's name, 2. Have "the" affixed to the word ال as a prefix, 3. Have a possessive suffix (my, your, his, her, etc.) 4. It is a part of a definite Noun-in-Construct (known in Arabic as an "iDaafa"). A noun-in-construct is when something belongs to something or someone else. In English, we might say "car of the professor" or "professor's car".
Nouns take a case. In Arabic, this is a short vowel that identifies what the noun's role is in a sentence. Adjectives will take the same case (and exact same ending) as the noun it describes. We do not pronounce the case marker (even when pronouncing the case markers of other words) for a given name. Reading religious texts (especially Islamic texts) is an exception when everything is read.
Nominative case identifies a "subject". This is the noun that is performing the action in question. This is also the "default" case for individual words and anytime the other cases do not apply. In Arabic, the Nominative case is identified by a Damma or "u" on the last letter of a definite word or a Dammatain or "un" on the last letter of an indefinite word.
Accusative case identifies a "direct object". In Arabic, there needs to be a written verb that "directly" affects the object (no prepositions intercede). The verb "to be" in the present tense is rarely written and therefore does not cause a noun or adjective to become accusative. In Arabic, the Accusative case is identified by a Fat-Ha or "a" on the last letter of a definite word or a Fat-Hatain or "an" on the last letter of an indefinite word.
Genitive case identifies the "indirect object". This applies to nouns (and adjectives that describe these nouns) that come after a preposition or are any word in a "Noun-in-Construct" (aka "iDaafa") other than the first word. In Arabic, the Genitive case is identified by a Kesra or "i" on the last letter of a definite word or a Kesratain or "in" on the last letter of an indefinite word.
If you choose (or are required to) pronounce the case marking short-vowels and the word ends in a Taa-Marbutta ة, it is also required to pronounce the "t" sound that results.
The sentence above can be pronounced:
Full Pronounciation with all vowels: Im-ra-a-tun dha-kiy-ya-tun wa-ra-jul-un dha-kiy-yun.
Regular Pronounciation (almost all times outside of quoting religious text): Im-ra-ah dha-kiy-ya wa-ra-jul dha-kiyy.
When there is "Nunation", although the "N" sound does appear at the end of the indefinite nouns and adjectives (when pronounced), we do not write the letter Nuun ن.
I hope that this helps to clear up things.