Curry is neither a spice nor a spice mix.  It's just a sauce with spices in it. 

Around the middle of the eighteenth century, the British defeated the Mughals & began their colonization of India.  They borrowed the term ‘curry’ from the Portuguese who described ‘caril’ or ‘caree’ as any broth Indians made with butter, nuts, vegetables & a multitude of spices.

In an attempt to capture the overwhelming variety of "broths", the English classified curries as Bombay, Ceylon or Madras. This broad categorization missed the subtle variations & nuances of each preparation across the many kitchens of India. 

To the British, curry was not just a term that described an unfamiliar Indian approach to food, but a dish in its own right created for the British in India. Outside restaurants, the word ‘curry’ is practically non-existent amongst Indians. There are specific names for broths, braises & stews which cannot be simplified as just a curry.  

Curry powder, a commercially prepared mix of spices (mostly turmeric, cumin and coriander), is a Western notion dating to the eighteenth century. It was first prepared & sold by Indian merchants to members of the British Colonial government & army returning to Britain. 

No self-respecting Indian cook uses curry powder! If you have any in your pantry, throw it out unless it is fresh & well-sourced. Indians may use upwards of ten spices in one dish but they are all added individually & at different times in the preparation.  They may be used whole, ground, toasted, crushed, or just popped in oil to release flavor.