This might be a fun way to keep my Greek going and pick up some Latin along the way. If we're doing groups of three though, I might have to fill in the third slot with a random other I-E language.
Greek: αἰών "eternity, age"
Latin: aetas "eternity, age"
English, Middle & Modern: age
It would also be nice if this was open to more then just Indo-European language families. On that note, here are some Semitic cognates to help me with Hebrew, Aramaic and Arabic at the least.
Aramaic: סגד [sgd] "he bowed"
Arabic: سخد /sajada/ "he bowed"
Hebrew: שָׁחֹה /šaħoh/ "he bowed"