a hard nut, a hard nut to crack, a hard row to hoe, a tough cookie, a tough nut, a tough row to hoe, be as tough as old boots, tough as an old boot, tough as nails, tough cookie, tough customer
You cannot count them because new idioms are constantly being invented all over the world.
savvy, brainy
Not always. Sometimes idioms are just phrases.
Some words that describe space are:vastvoidcryptic
Try this question for examples of idioms.
"Idioms for Being Afraid", "Idioms for Being Angry", "Idioms for Being Happy" are some examples of idioms found in the book "Found" by Margaret Peterson Haddix.
Looking tough
One idiom describes being in love as being "head over heels."
There are many idioms and phrases for 'on the back burner'. Some idioms and phrases for 'on the back burner' include 'pushing aside' and 'procrastinating'.
You cannot count them because new idioms are constantly being invented all over the world.
Some websites that have idioms written in them include The Free Dictionary, Cambridge Dictionary, and Phrases.com. These sites provide definitions and examples of idioms to help users understand their meanings and usage in context.
Here is a link to some idioms. You can pick the "non-common" ones for yourself -- some people have heard certain idioms a lot and others have not heard the same ones, so you'll need to decide that part.
savvy, brainy
The best place is to go on your search engine and type in "list idioms" You can also look at this question for some examples.
Some examples of idioms in "Divergent" include "jumping off the deep end," "barking up the wrong tree," and "walking on eggshells." These idioms are used to convey deeper meanings or emotions within the story.
cry unclemonkey's uncle