A) Can you describe exactly what it is for someone to have a headache, basically saying what the word headache means?

A) Can you describe exactly what it is for someone to have a headache, basically saying what the word headache means? What are the criteria that are individually necessary and collectively sufficient that would be true if the sentence "Jones has a headache" is true? What is it we know about anyone who truthfully reports they have a headache?  allheadache