|Things to be obligated for...|
It was delicious and fun with more than 30 people and 15 kids. The kids put on a Thanksgiving play explaining the meaning of Thanksgiving, and afterwards, mulling over the word "thanksgiving" and its origin (I will admit to two glasses of wine by this time), I also thought about thanking people in Portuguese. Meaning, how you say "thank you."
When thanking someone for service or whatever in a store or restaurant, I say "obrigada" while my husband says "obrigado." Literally it means that you are "obliged" to the person who has provided the service. As far as I can tell, the origin of the shortened "obrigado" is "estou-lhe obrigado" or "I am obliged to you." Or, more crassly, "I owe you one."
The word "agradecer" in Portuguese is probably the more direct translation of "to thank" but it is not used in most casual conversation. You do see it often in formal written letters--"eu agradeço a atenção" would mean "I thank you for the attention." I don't use it much because for whatever reason I trip over the vowels and it never comes out right.
One of the complexities of "obrigado" is how you respond to the person who says it to you. Most commonly you respond "de nada" or "foi nada" (it was nothing) but sometimes, if you want to say "thank you" back to the other person, you could slide in "obrigada eu" or "I am obliged to you". Sometimes you hear an "obrigada voce" which is meant as "thank you back" but actually means "you are obliged to me". I got the bad habit of saying "obrigada voce" before I knew that it was incorrect, and it is the devil to take it out of my speech. As BH explained to me "obrigada a voce" is correct but you need that "a" in there to make it "I'm obliged TO you." Whew, this is complex stuff.
In any case, I am much obliged to our friends for a lovely day. Obrigada eu.