Answer :

The word delta is usually defined as a mass of sediment usually of triangular shape found the mouth of a river. Some of the examples are the Nile River’s delta and the Mississippi’s delta. Delta  is also defined as highly skilled and effective soldiers. They are skilled with all weapons systems and tactics. They have mastered at least two languages. As for their behavior, they are extremely polite and educated, they won't pick fights.  
When used in the sentence:
1.  
The delta of the Mississippi River is mainly the state of Mississippi.

2.   A delta is a well-trained and one of the toughest person in the world.  


Answer:

Deltas' greatest importance to human activities, fish and wildlife lay in their characteristic highly fertile soil and dense, diverse vegetation. In order to fully appreciate the role deltas play in our larger ecosystem, it is first important to understand rivers.

Explanation:

Upper-case delta (Δ) often means "change" or "the change in" in mathematics. For example, if the variable "x" stands for the movement of an object, then "Δx" means "the change in movement." A delta is a wetland area created by the build up of sediment where a river empties into a larger body of water. ... Deltas get their name from a Greek letter of the alphabet, and there is evidence that deltas can exist on other planets. The delta arms sometimes remain blocked with ice the whole year round. The most fertile soil is the alluvium of the' Delta, deposited during the overflows of the Mississippi.