shudder, shutter

Shudder or shudder means a sort of shaking or convulsive involuntary physical movement, from cold, fear, or horror--
A shudder ran through him when he heard the eerie creaking sound.
"It's cold", she said with a shudder.

Shutter or shutter means one of the two pieces of wood that closes over a window, or one of a decorative pair that doesn't close--
This shutter fell down, and now there is only one left hanging there. Can you fix it?
Just close one shutter, and we'll have some light from the open one.

Shutter or shutter may also mean the part of a camera that opens and closes, to admit light and expose the film--
You might be able to catch a picture of the dog running if you use a faster shutter speed.

Now that you know that, you can say--
"A shudder ran through me when I heard the groaning sound, but it was only the wind blowing the shutter."

Note--Not to be confused with "shut her" meaning close ( shut ) [something] belonging to a female ( her )--
Tell her to shut her mouth.
She shut her hand in the door.

crock, croc

Crock or crock means a stoneware or pottery jar, pot, or container--
There is more butter in a crock on the pantry shelf.
Make sure to save the crock the cheese came in. I want to use it as a planter.

Croc or croc ( rhymes with crock ) is an informal or familiar term for "crocodile", meaning thr animal similar to an alligator--
He never saw the croc coming. It bit him before he had time to shoot.
That's not a floating log; it's a croc!

Now that you know that, you can say--
"That old crock is full of his souvenirs, including a small croc he once caught, dried and stuffed."

bookends, book ends

Bookends or bookends ( one word ) means a pair of heavy objects used to keep books standing up on a shelf, desk, or table--
He has two old bronze gargoyles on his desk, for bookends.
Two bricks make useful, utilitarian bookends.

Book ends or book ends ( two words ) is the third person singular ( he, she, it ) form of "end", meaning to come to a conclusion or to  finish, said of  a literary work of some kind ( book )--
Don't tell me how this book ends! You'll spoil it!
I can't wait to find out how this book ends!

Now that you know that, you can say--
"The book ends when the detective discovers the body of a man murdered with one of his own bookends."

Note--"books end" means the finish or conclusion ( end ) of more than one literary work ( books)--
Many of his books end with a surprise.
Note # 2--"book's end" means the finish or conclusion ( end ) belonging to one particular literary work ( book's )--
This book's end is a real shocker!
Note # 3--"books' ends" means the conclusions ( ends ) belonging to more than one literary work ( books' )--
This authors books' ends are always exciting. [ awkward but logical ]

elusive, illusive

Elusive or elusive means mentally difficult to grasp, eluding a clear perception or understanding--
The concept of democratic government may remain elusive, unless the students are offered real-life illustrations and examples of how our government works.
Algebra seems elusive, until practice makes the idea of a variable seem logical.

Elusive may also mean difficult to catch, or skillfully evasive--
"Across my dreams, with nets of wonder, I chase the bright elusive butterfly of love..."
He got a hook into the elusive old trout, but it got away.

Illusive or illusive means decptive or unreal--
They spent years searching for the illusive fountain of youth.
The illusive philosopher's stone was said to be used to turn lead into gold.

Now that you know that, you can say--
"He is trying to explain an elusive concept that many people believe to be illusive."

Note--"illusory" is more commonly used than "illusive"; it has the same meaning--
Your fears are illusory; the noise was only the wind.
Note # 2--"elusory" is less commonly used than "elusive"; it has the same meaning--
These concepts won't be elusory if you work on a lesson that is age-appropriate.

ascertain, as certain

Ascertain or ascertain ( one word ) means to make sure of a fact or facts; to find out definitely--
Before we begin the investigation, we'll call the coroner, who will ascertain the cause of death.
Let's call them in, so we can ascertain the facts before we make a decision.

As certain or as certain ( two words ) means to some extent, measure or limit; equally ( as ) sure or free from doubt ( certain )--
I am as certain of the spot as if I had been there only yesterday.
There's not a doubt in my mind--I'm as certain of his capability as I am of my own.

Now that you know that, you can say--
"I won't feel as certain of his guilt as the rest of you are until I can ascertain that he had a motive for the crime."

Note--"a certain"  ( two words ) describes one ( a ) thing or idea that is definite or particular ( certain )--
She has a certain tone that lets you know she's annoyed.
"A certain smile, a certain face..."

solo, so low

So low or so low ( two words ) means very, or to the extent specified ( so ) near the ground or surface, or small in measure or number ( low )--
The temperature is so low that the pond is frozen over.
The table is so low that we'll have to sit on the floor to eat.
So low may also describe a very deep ( low ) voice--
Her voice is so low; people are surprised when they meet her and see how small she is.

Solo or solo ( one word ) means a musical  number or act written for or performed by one person--
She does a wonderful solo in the second act.
He wants to sing a solo, but the director won't let him unless he promises to practice.

Solo may also mean alone, in a general sense, or without a companion or copilot--
She has been solo since her husband died three years ago.
This is his first solo flight, and he's nervous.

Now that you know that, you can say--
"He was asked to sing a solo, but the pay was so low that he refused."

nobody, no body

Nobody or nobody ( one word ) means no one; not one person--
We were supposed to have a meeting, but nobody showed up. 
I knocked, but nobody answered.

Nobody is also an informal word meaning an unimportant person; someone with no status or connections--
He didn't want his friends to see him talking to a nobody.
He's a real nobody; she doesn't even know he's alive.

No body or no body ( two words ) means not any ( no ) corpse or cadaver ( body )--
It will be difficult to prosecute a murder case, with no body.
We couldn't have a funeral with no body, so we just had a memorial service.
No body also means not any ( no ) consistency or substance ( body )--
I bought this product because my hair has no body; it won't stay in place.
This fabric has no body; we'll have to put a lining in the jacket so it will hold its shape.

Now that you know that, you can say--
"He wore a mask and a black robe, so he's look like a head with no body, but nobody was frightened."