The word chair came into English from the old French chaire created fom the Latin cathedra (cadeira --> chaere), which is related to the Greek καθÎδÏα (kathedra; chair, seat).
From the same root: cathedra, cathedral, ex cathedra
In modern Greek:
a) καθÎδÏα: cathedra [kathedra]
β) καθεδÏικός (ναός): cathedral [kathedrikos naos]
γ) από καθÎδÏας: ex cathedra [apo kathedras]
καθÎδÏα (kathedra) - cathedra --> cadeira --> chaere --> chaire --> chair
See the blog 'English words of no apparent Greek origin' at: http://ewonago.blogspot.com/
