THOUGH/THOUGHT/TOUGH/THROUGH/THRU*/THROUGHOUT/THOROUGH...What's the difference?

One of the most challenging aspects of English is spelling.  Let's take a look at the following words, one at a time, according to pronunciation and meaning/grammar along with some examples.

In terms of pronunciation, I will NOT be using the International Phonetic Alphabet (IPA) because many readers are not familiar with it.  Instead I will be using audio links to Cambridge Dictionary online, where both American and British English pronunciations are demonstrated.

THOUGH--THOUGHT--TOUGH--THROUGH--THRU*--THROUGHOUT--THOROUGH

1. THOUGH (conjunction)

Pronunciation: http://dictionary.cambridge.org/pronunciation/british/though

Meaning/Grammar: Though is synonymous with but and although.  

Ex. Though I really like hot weather, 40 degrees Celsius is way too hot for me! 

2.  THOUGHT (verb)

Pronunciation: http://dictionary.cambridge.org/pronunciation/british/thought

Meaning/Grammar: Thought is the past tense of think. 

Ex. I thought about your proposal, but I can't accept it. 

3.  TOUGH (adjective)

Pronunciation: http://dictionary.cambridge.org/pronunciation/british/tough

Meaning/Grammar: Tough is synonymous with hard, difficult, firm or strict.  

Ex. My English test was tough. 

Ex. My grandfather is tough...he is 90 years old and still works in the field 8 hours a day!

4.  THROUGH (preposition)

Pronunciation: http://dictionary.cambridge.org/pronunciation/british/through

Meaning/Grammar:  From one end or side to the other; from beginning to end; because of someone or something; from one time until another. 

Ex.  First go through the tunnel, and then turn right.  

Ex.  I worked through the night to finish the translation.  

Ex. I got my job through my father-in-law.  

Ex. The bank is open from Monday through Saturday.

5.  THRU (preposition) *This is NOT Standard English...do not use!

Pronunciation: http://dictionary.cambridge.org/pronunciation/british/thru

Meaning/Grammar: Again, this is NOT Standard English.  It is a poor and easy spelling of the word through, as seen above.  The only proper use of this word is in the word "drive-thru".  

Ex. Whenever we eat at McDonald's, we use the drive-thru. 

6.  THROUGHOUT (preposition)

Pronunciation: http://dictionary.cambridge.org/pronunciation/british/throughout

Meaning/Grammar: In every part or place; during an entire period of time.  

Ex. The disease spread throughout the population with two short weeks.  

Ex. We listened to the lecture throughout the afternoon. 

7.  THOROUGH (adjective)

Pronunciation: http://dictionary.cambridge.org/pronunciation/british/thorough

Meaning/Grammar: Thorough is synonymous with careful, complete, meticulous, detailed, organized. Ex. Translation work requires a person to be thorough and detailed.  

I hope this helps!  Thanks for reading :)