"Nude" originally had a meaning of
'plain, bare, unadorned' in a broader sense when introduced into
English from Latin nudus, originally only as a legal term
'unsupported by proof' since 1531, only used an artistic euphemism
for physical nakedness in 1631, while "bare" and "naked" derive from
the common early English words, with many cognates, for
'uncovered'). Some consider one term more appropriate than the
other. The book Nude, Naked, Stripped suggests that these three
terms define a continuum ranging from artistic or tasteful absence
of clothing by choice at one end, to a forced or mandatory condition
of being without clothes (e.g. strip search) at the other.
As the concept of nudity often refers
more to perception by the observer than the mere description whether
someone's body is covered or not, there can be a grey area, known as
partial nudity. Thus, while someone exposing 'private parts' is
often called 'naked' regardless of garments on other body parts
(indeed, an 'undressed' state is even considered by some more
sexually arousing than full nudity) hence the terms half-naked and,
a fortiori, near-naked refer to a body that is not completely
exposed, but showing more than is customary or considered quite
acceptable, at least in a given context. However the quantity of
skin exposed is not the determining criterion, it's the "quality"
that counts for perception..