The original meaning of the word 'mind' was the capacity of memory.

Then, beginning in the 14th century, gradually the meaning broadened and is now considered to include our mental faculties of thought, imagination, memory, will and sensation - which are responsible for perception, experience, belief, desire, intention, and emotion.

And of course we are only aware of the content, faculties and activity of mind when they arise into our conscious awareness.

So, the mind is far, far more than just 'thinking', as most believe it to be.