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.
1. THOUGH (conjunction)
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)
Meaning/Grammar: Thought is the past tense of think.
Ex. I thought about your proposal, but I can't accept it.
3. TOUGH (adjective)
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)
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!
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)
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)
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 :)