Fool>Foolish>Fooling around

>fool (v.) means to deceive or trick

someone
For example, sometimes kids pretend to be sick in order to fool their parents into letting them stay home from school.

>fool (n.) refers to a stupid person without good common sense.
For example, a guy who buys a new car and immediately drives too fast and crashes it into a tree. He could be described as a fool.
>>Note: Calling someone a fool is similar to calling the person an idiot; it is an insult and would be considered offensive, so be careful about applying this label to people.

>foolish (adj.) describes things that lack good sense/judgment.
For example: he made the foolish decision to drop out of college in his final semester, with $100,000 of student loan debt. That decision was not very smart!

>fool around (v.) can mean to act casual and silly, or to have a casual sexual relationship.
For example, if all your co-workers are chatting about last night’s sports game and showing each other vacation pictures, your manager might say “Stop fooling around and get back to work!”
Another example, Sally divorced her husband Joe because he was fooling around with a woman he met at the gym. This means Joe was having a casual sexual relationship with the other woman.