'Though' means "although"; 'thorough' means "careful and complete". They share almost every letter but nothing else.
"Though" is a conjunction meaning "although", used to contrast two ideas, either mid-sentence or at the end of one.
The movie was long, though I didn't mind because I loved it.
I'm not hungry. I'll eat something small, though.
Though it was raining, they still went hiking.
"Thorough" is an adjective describing something done carefully and in detail, leaving nothing unchecked: "a thorough investigation", "a thorough cleaning".
The inspector did a thorough check of the entire building.
She gave a thorough explanation of how the process works.
We need a thorough cleaning before the guests arrive.
Common mistake
Writing "thourough" or mixing it up with "though" when you meant "careful and detailed" is a very common spelling mistake, since the two words share nearly all the same letters in a different order. "Thorough" has an extra syllable and ends in "-rough", not just "-ough".
Trick to remember it
"Thorough" has two syllables (THOR-ough) and sounds a bit like a small tour through every detail. "Though" is one quick syllable, short like the "although" it stands in for.
Quick rule
Is it "although", contrasting ideas? "Though". Is it "careful, complete, detailed"? "Thorough".
Did you know?
"Thorough" is actually an old variant of "through": in Middle English, "thorough" and "through" were basically the same word, used interchangeably to mean "from start to finish". Over time, English split them apart: "through" kept the literal sense of crossing a space, while "thorough" evolved into the figurative sense of doing something "from start to finish, leaving nothing out", meaning thoroughly.
Exercise 1 · Pick the right one
The doctor did a _____ examination before giving her diagnosis.
Exercise 2 · Pick the right one
I didn't love the restaurant, _____ the dessert was amazing.
Exercise 3 · Form the word
'Through' means "from one side to the other"; 'though' means "although". They look similar but have nothing in common.
One means to receive or agree to something, the other means to exclude or not include.
'Advice' is the guidance you receive (noun); 'advise' is the act of giving that guidance (verb).
'Affect' is the verb meaning to influence something; 'effect' is the noun meaning result or consequence.
Bryan López
Founder of SpeakUP Academy