any fossil plant of the genus Calamites and related genera of the Carboniferous Period, resembling oversized horsetails and constituting much of the coal used as fuel.
Origin: 1745–55; < NL Calamites the genus name, L calamītēs < Gk kalamtēs reedlike. See calamus, -ite1
[kal-uh-mahyt] 
əˌmaɪt
tēs