This is always a pain-in-the-ass to explain because it's one of those complete linguistic fuckups.
It refers to a specific herb but also to a specific spice mixture. Most of the time it's the latter not the former but it still requires a ton of explanation every single time.
These linguistic faux-pas are not entertaining.
This one is the mixture.
It's terrific baked as a bread topping or even just for dipping with fresh pita bread.
2 tbsp. dried oregano (preferably Mexican oregano)
2 tbsp. sesame seeds (lightly toasted)
1 tbsp. crushed sumac.
1 tbsp. dried marjoram
Crush in a mortar and pestle and mix together.