Assignment 2 - Dictionary Exercise

I have been trying to get these two words straight, that is, cohesion and coherence.

I know that these two words have always been used on writing, but I Always confuse with them.

So....I tried several on-line dictionaries to look them up, but none of them can provide me a satisfiing answer...until this one - http://dictionary.reference.com/

Firstly, the following is the definition of "cohesion"

noun

1. the act or state of cohering, uniting, or sticking together.

2. [Physics.] the molecular force between particles within a body or substance that acts to unite them. Compare adhesion (def. 4).

3. [Botany.] the congenital union of one part with another.

4. [Linguistics.] the property of unity in a written text or a segment of spoken discourse that stems from links among its surface elements, as when words in one sentence are repeated in another, and esp. from the fact that some words or phrases depend for their interpretation upon material in preceding or following text, as in the sequence Be assured of this. Most people do not want to fight. However, they will do so when provoked, where this refers to the two sentences that follow, they refers back to most people, do so substitutes for the preceding verb fight, and however relates the clause that follows to the preceding sentence. Compare coherence (def. 5).

Then, compare another word "coherence"

noun

1. the act or state of cohering; cohesion.

2. logical interconnection; overall sense or understandability.

3. congruity; consistency.

4. [Physics, Optics.] (of waves) the state of being coherent.

5. [Linguistics.] the property of unity in a written text or a segment of spoken discourse that stems from the links among its underlying ideas and from the logical organization and development of its thematic content. Compare cohesion (def. 4).

See, the comparison under the category [Linguistics] is exactly what I want. This on-line dictionary provides different definitions on each categories, such as Physics, Botany, and Linguistics, etc. Besides, it posts links of the confusing word on it. Isn't it useful?