We usually translate ‘anupassanā’ as “contemplation,” thus ‘kāyānupassanā’ as “contemplation of
the body,” but this might be somewhat misleading. It might be more accurate, and more
literal, to translate it as “observation.” The word is made up of a prefix ‘anu’ which
suggests repetition, and ’passanā’, which means “seeing, viewing.” So sati is part of a
process that involves a close, repetitive observation of the object.
I like Bhikkhu Bodhi's use of the word "observation", which I think gives a good feel for the actual experience. Sometimes I describe it as "paying attention."
"My religion is very simple - my religion is ice-cream."