Correct. We are on the same page. All living things by definition exchange gases (i.e. "breathe"). The ancients knew that intrinsically. That process stops when the living things become dead.
SOUL. The thinking principle; that by which we feel, know, will, and by which the body is animated. The root of all forms of vital activity. It is a substance or a being which exists per se; it is simple or unextended, i.e., not composed of separate principles of any kind; it is spiritual, i.e., its existence, and to some extent, its operations, are independent of matter; it is immortal (q.v.). The soul is the substantial form (q.v.) of the body. There are three kinds of soul, vegetative, the root of vital activity in plants; sensitive, the root of vital activity in animals; intellectual, the root of vital activity in man. The last contains the other two virtually (q.v.); the sensitive contains the vegetative also virtually. The sensitive and vegetative soul are both simple, but incomplete substances, incapable of existing apart from matter; they are therefore neither spiritual nor immortal...--Donald Attwater, Ed., A Catholic Dictionary, The MacMillan Company (1942), w/Nihil Obstat & Imprimitur, pp. 497-98