adjective, ach·i·er, ach·i·est. having or causing an aching sensation: an achy back.

What does achiness mean?

achiness in British English

(ˈeɪkɪnəs) a constant, dull pain. flu-like symptoms, such as fever, fatigue, headache and achiness in muscles and joints.

Is there such a word as achiness?

Definition of achiness in the English dictionary

The definition of achiness in the dictionary is a constant, dull pain.