Meanings
- 1thank you (for the meal); that was a delicious mealinterjection
- 2thank you (for displaying lovey-dovey behaviour)interjection
JMdict 1270520
In a sentence
ごちそうさまthanks for the mealでした、おいしかったwas delicious
Thanks for the meal, it was delicious
How it works
ごちそうさまでした (thanks for the meal) is a set phrase said after eating — its でした (was) is the past polite ending, so it always comes out in this fixed shape. Then comes the verdict: おいしい (delicious) is an i-adjective, and to put it in the past you drop the final い and add かった, giving おいしかった (was delicious). There's no subject — the meal is understood — so the bare adjective stands alone, sounding warm and a little informal after the polite opener.