Abarim Publications' online Biblical Greek Dictionary
The noun καλαμος (kalamos) means reed or stalk, or anything made from reeds — anything from roof covering to flutes, arrows, fishing rods, measuring rods, rods for support of vines and of course, pens to write with. In the Old Testament, reed often refers to papyrus, from which paper was made (see our article on βιβλος, biblos, paper).
Our noun comes from an ancient Proto-Indo-European root meaning the same, with the same broad application. In Matthew 12:20 our noun καλαμος (kalamos) translates the Hebrew noun קנה (qana), whose root is identical to a verb that means to create or purchase; hence the names Cain, Canaan and Cana.
Our noun καλαμος (kalamos), reed, is used 12 times in the New Testament; see full concordance.
The noun καλαμη (kalame) is the feminine version of καλαμος (kalamos) and refers to the same material, albeit somewhat broader and more conceptual. To compare: the feminine noun πετρα (petra) means rock in the sense of a vast mountain or endless layer of rock, whereas the masculine noun πετρος (petros), hence the name Peter, refers to a loose pebble. Still, when the description is of stubbles, residue left after the harvest, or an altogether ruined crop, this feminine word tends to be used. This in turn enticed early etymologists to connect our noun καλαμη (kalame) with the familiar Latin noun calamitas (calamity), but that's no longer considered correct, since calamitas rather relates to the verb κλαω (klao), to break.
Our noun καλαμη (kalame) occurs in 1 Corinthians 3:12 only.