Definiteness is a semantic feature of noun phrases, distinguishing between referents/entities that are identifiable in a given context (definite noun phrases — in English marked with determiners such as “the,” “this,” “every,” and “both”) and entities which are not (indefinite noun phrases — in English marked with determiners such as “a/an,” “many,” “any,” “either,” and “some”). (source: Wikipedia)

“[As an example,] the English and Choctaw concepts of how definiteness and specificity are handled are not mapable to each other, even though the mechanism for the marking itself, a set of affixes, is quite simple.

“English wrings as much work as possible from the articles ‘a’ and ‘the’ and a few other demonstratives. A native speaker knows how to use these to refer to new information, to things already in evidence, to particular things, and to general members of a set. If these will not pick out something to a fine enough degree, we also can use a range of other constructions, such as relative clauses, adverbs, and even idioms to make finer distinctions. But these are not grammaticalized, they are tools the speaker may use to clarify an utterance, not mandatory.

“In strong contrast, Choctaw has a large, finely articulated, and morphologically efficient system to mark definiteness, contrast, specificity, and the like. A large set of affixes marks information about how specific something is, whether it has been mentioned previously, when in the discourse it was mentioned, whether it contrasts with something else in the discourse, how particularly it contrasts, whether it is part of a set, and other distinctions that are literally not possible to categorize in English.

The result in translation is that at some point, not only do English words fail, but some of the distinctions cannot even be made in a meaningful way. More precisely, we can perhaps capture the essence of the Choctaw distinctions, but only at the cost of a cumbersome sentence that would never be uttered by an English-speaker.” (Source: Marcia Haag in Swann 2011, p. 352f.)

Following are some examples from a Choctaw translation from 1881 (with the respective definiteness markers underlined):

The Greek that is translated as “when he came into the house” in English is translated as Milnna yυmmak ash osh aboha ont chukowa ma: “And when the one being discussed entered the room.” (See Mark 9:28)

The Greek that is translated as “the girl got up” in English is translated as ohoyo himita yash osh tani tok: “that young woman, the one being discussed, arose.” (See Matt 9:25 and Mark 5:42)

The Greek that is translated as “we know God spoke to Moses” in English is translated as Moses ak okvno Chihowa yυt im anumpuli beka tok a il ithana: “We know that Moses the particular one in contrast to others was the one whom Jehovah the definite subject of this clause used to speak to.” (See John 9:29)

Source: Haag / Willis 2007, p. 124.