Please explain this?
Why is "Die Frau hat einen Elefanten" correct, while "Die Frau hat ein Elefant" is wrong? I never understood when einen was used instead of ein, and where did the extra "en" come in Elefanten?
"einen Elefanten" is the direct object of the sentence. Hence, it takes the accusative case. http://www.pauljoycegerman.co.uk/abinitio/chap3-6.html
WHY "EINEN" AND NOT "EIN"?
As has already been explained, when you have a singular masculine noun like "Elefant" or "Mann", "ein" is used if the noun is the subject and "einen" if the noun is the direct (accusative) object.
Ex. "An elephant is big". In this sentence, "an elephant" is the subject, because it is active, i.e. it is "doing" or "being" something. Thus, you have to use "ein": "EIN Elefant ist groß."
Ex. "The woman has an elephant." In this sentence, the elephant is the direct (accusative) object, i.e. it is passive and not doing something. Thus, you have to use "einen": "Die Frau hat EINEN Elefanten."
WHY "ELEFANTEN" AND NOT "ELEFANT"?
Normally, you just have to change the article if a noun is used as a direct (accusative) object. The noun itself does not change: "Ein MANN ist groß" [A man (= subject) is big] and also "Die Frau sieht einen MANN" [The woman sees a man (= direct object)].
However, there is an exception: a small group of nouns always add an "-n" or "-en" when they are used as objects. These nouns are called "weak nouns" or the "n-declension". The word "Elefant" belongs to this special group. As I said, this is an exception and not the norm.
See here (note that they misspell "Elefant", but the explanations otherwise seem to be okay): http://www.vistawide.com/german/grammar/german_nouns03.htm
See also the entry by the person who posted above you. He or she mentions exactly the same exception.
@esom: Thanks, also for the interesting link! About the spelling: "Elephant" is not listed in Duden, the authoritative reference work for German spelling. It is also not listed in the DWDS Wörterbuch in your link. Duden also has a website, so you don't have to take my word for it :): http://www.duden.de/suchen/dudenonline/Elephant In your link, there are some examples of the spelling "Elephant", but they all either date from around 1900 or are proper names ("Hotel Elephant"). The spelling with "ph" is dated, i.e. wrong in a modern text (when referring to the animal).