A pill is a small solid medicine you swallow with water. It helps you feel well if you are sick or have pain.
I take a pill when I have a headache.
She swallows a pill every morning.
In science, a pill can be a small ball of a chemical or substance used for experiments or medicine making. It is not usually swallowed.
The chemist measured one pill of the powder.
A pill of salt was added to the solution.
To pill means to remove small balls or fluff from clothes. People do this to make old clothes look nicer and cleaner.
I pill my old sweaters to keep them clean.
She pilled the shirt before wearing it.
To pill someone means to make them angry or annoyed on purpose by not being kind or fair. It is often used in informal speech.
He always pills me when I am busy.
Stop pilling me about my homework.
A pill is someone or something that is very annoying or difficult. People use this word when they are unhappy with others or problems.
He is a real pill to work with.
That broken phone is a pill for me.