Is there a name for X when X bitwise OR Y is Y?

I’m wondering if there is a mathematical or computer science term for a number X such that Y | X = Y? For example:

66536 | 1000 == 66536 

In this case, 1000 is the "insert name here" of 66536. Perhaps there is no name for this..? I’ve tried searching for "bitwise OR returns itself" and other such terms but without luck so far.