deh-TAHN-drə
Breakdown:
* deh: Similar to the "day" in "daytime," but with a slightly shorter vowel sound.
* TAHN: Like the "tan" in "tantrum," but with a slight emphasis.
* drə: Similar to the "duh" in "dull," but very short and almost silent.
You can listen to the pronunciation on online dictionaries like Merriam-Webster or Forvo.