CANON: The English word "canon" originally referred to church law and later came to refer to the accepted books of the Bible. Then, by transference, it now means any set of sacred books or books regarded as having an especially authoritative standing, such as a literary canon. It is from the Greek word
kanon, which means a straight bar or a rule. When a saint is "canonized," it means that the saint has been added to the canon of saints, i.e. the official list of saints commemorated in the calendar.
CANNON: A "cannon" is a weapon, a tube from which projectiles are fired. It is from the Italian
cannone, which is in turn from Latin
canna, meaning a reed or tube.