The word unreasonable describes actions or thoughts that do not make any sense or are inappropriate. Therefore, the word unreasonable is a synonym for absurd.
While everyone has their own beliefs, it is unreasonable to say that animals cannot show kindness and compassion. Dogs and cats are some of the most kind animals in the planet.
Susan thought Josh was being unreasonable when he brought an umbrella to the desert. She reminded him that there was almost a 0% chance of rain in that part of the world.
An idea or thought that is absurd is said to go against all reason. Anything that goes against all reason can be easily disproved or showed to be wrong.
It goes against all reason to believe humans can live over 200 years. Our bodies are just not made to live that long and start wearing down way before that time.
Susan asked us if we thought our head teacher was a ghost. We told her it goes against all reason to think such a thing because she talks to us and shakes our hand every day.
Anything that is illogical goes against truth, fact, science, and reason. Therefore, the word illogical is a synonym for absurd and unreasonable.
Before you say anything in class, make sure you have evidence or reasons to support your idea. You could get in trouble or lose points for saying something illogical.
Jared had always wanted to be a famous guitar player. But his dream was illogical because he had never even tried to play a guitar himself. In fact, he didn't even really like music.
The opposite of illogical is logical. Any action or idea that makes sense or is supported by fact, science, or reason is considered logical.
Will thought it was perfectly logical to spend a week studying for his math exam. He knew the more effort he put in, the better he would do on the final grade.
It is logical to believe you could get hurt if you go hiking without wearing the right shoes. Without hiking boots, just one small fall could cause a foot injury.