There's a popular (and probably exclusively) guatemalan expression: deplano or de plano; meaning probably or surely, analogue to seguramente.
Example (provided for completion purposes):
-¿Dónde está Juan?
-Deplano se fue a comer.
Now, this might be a too colloquial or informal word to have its own official spelling, but I still wonder if there is a "proper" way to write it. My gut tells me it should be written as a single word, but it's easy to get orthography wrong.
Also, if you know of other places where it's said, please comment!