Linear B:
Linear B is a syllabic script used by the Mycenaean Greek to write. It predates the Greek alphabet several centuries but is the earliest form of Greek. It came after Linear A, but unlike Linear A was cracked by Alice Kober. It was very important for Greek linguists and was founded in Greek.
Thetes
Thetes was the lowest social class of citizens. They were workers for wage and or had to earn less than 200 medimnio as their yearly income. They had no political role but could vote. Their importance grew as their military status increased with the Delian League.
Barbarians
Barbarians were members of people not belonging to one of the great civilizations- Greek, Roman, Christian). Were called uncivilized and term coined around 300BCE. Initially referring to people who were from out of town/city or not a Greek speaker.