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Re: VEN [ΔΕΝ] versus OXI
by Greg Brush - Tuesday, 11 November 2008, 08:13 AM
  δεν is the negativizer used with verbs in the indicative mood:
δεν είμαι = I am not
δεν καταλαβαίνω = I don't [do not] understand
Δεν έγραψα εκείνο το γράμμα. = I didn't [did not] write that letter.
Δεν θα πάω. = I won't [will not] go.

Otherwise, όχι is used as the negativizer for adjectives, adverbs, nouns, or other parts of speech, as well as by itself to mean "No":
όχι πολύ = not very
όχι τώρα = not now
όχι εδώ = not here
όχι πράσινο, αλλά κόκκινο = not green but red
Όχι, Κυρία. = No, Ma'am.

Greg Brush