CO
n 1: a heavy odorless colorless gas formed during respiration and
by the decomposition of organic substances; absorbed
from the air by plants in photosynthesis [syn: {carbon
dioxide}, {CO}, {carbonic acid gas}]
2: a hard ferromagnetic silver-white bivalent or trivalent
metallic element; a trace element in plant and animal
nutrition [syn: {cobalt}, {Co}, {atomic number 27}]
3: one who refuses to serve in the armed forces on grounds of
conscience [syn: {conscientious objector}, {CO}]