What is a diminished chord? is it a 1, b3, b5 or 1, b3, 5, b7, or maybe its even b3, b5, b7??

I know its stupide but i must be sure
a diminshed triad is 1 b3 b5
a diminished seventh is 1 b3 b5 bb7
but what is often referred to as a diminished seventh is actually a half diminished seventh 1 b3 b5 b7 (you can build this one within in the regular major/minor scales)

1 b3 5 b7 is a minoth seventh