Without any doubt, Atom in Physics is not undividable: electrons around
the nucleus, and protons and neutrons inside the nucleus, and mesons binding
hadrons, and quarks and gluons inside both mesons hadrons, and W and Z bosons
showing-up from time to time, and neutrino, etc.
But "a-tomos" means in English "in-dividual" = un-divisible – a thing in
itself – a person. In this sense, in spite of the fact, that a body consists
of legs, arms, chemical elements, proteins, water and iron, a "person" remains
undividable.
Like Democritus’ A-tomos.
Ringrazio Mario Fedrizzi per suggerimento di questo tema