Watch out for the following words. They are easily confused, and a spell check will not necessarily help you with these.
They’re is a contraction of they are. Their is a possessive pronoun:
They’re writing their obituaries.
There refers to a place (compare where), whereas their is a pronoun that shows possession:
Their tombstones are over there.
Lose is a verb. Loose is typically an adverb:
If your wedding ring is loose, you might lose it.
However, sometimes loose can be a verb, in which case it means to set free, let go:
Jimmy loosed a shot at the keeper.
The ropes were loosed and the ship left the harbour.
When used as a verb, bare means to reveal and bear means to carry:
If you bare your bum, you will bear responsibility for the consequences.
Illusive (think illusion) means that something is deceptive, a mirage. Elusive means that something can’t be captured and escapes your grasp:
The ghost seemed elusive (hard to catch), but was really illusive (an illusion, not real).
These two have very similar meanings, but adverse (harmful, antagonistic) is not usually applied to people, whereas averse (loath, unwilling, opposed) tends to describe people’s feelings and is usually followed by to:
We faced adverse conditions on the high seas.
I guess I’m not averse to attending your Christmas concert.
The word tortuous means winding, full of twists and turns, and should be distinguished from torturous, though both can cause pain and suffering:
Reading your essay was a torturous experience, as I couldn’t follow the tortuous path of your argument.
Ascetic people abstain from the pleasures of the world. They practice self-discipline and lead an austere life. Aesthetics has to do with the study and appreciation of beauty:
His decadent aesthetics did not match my minimalist, ascetic lifestyle.
To compliment is to praise someone. To complement means to add something in order to improve:
“Your scarf complements your outfit.”
“Thanks for the compliment!”
Sometimes it can be difficult to keep words separate. Take disinterested. It’s primary meaning is unbiased or objective. Being disinterested therefore does not mean being uninterested. However, a quarter of all uses of disinterested do mean uninterested, which of course infuriates the purists. The point is that language change is driven by confusion and laziness, so, if you make a mistake, take heart: you may be making history.