Definition from Wiktionary, the free dictionary
Ancient Greek 
- (5th BC Attic): IPA: /dé/
- (1st BC Egyptian): IPA: /dɛ/
- (4th AD Koine): IPA: /ðe/
- (10th AD Byzantine): IPA: /ðe/
- (15th AD Constantinopolitan): IPA: /ðe/
Usage notes 
Δέ is a post-positive word, i.e. it is never the first word in a sentence. It is usually the second, but sometimes also the third or fourth.
It is often used together with μέν.