if something is uppermost in your mind, you think about it a lot because it is very important to you:
A feeling of pity for David was uppermost in her mind.
2 [not before noun]
more important than anything else:
The one word which seems to be uppermost in every discussion is money.
3 [usually before noun]
higher than anything else:
the uppermost windows of the house
She turned her hand over, palm uppermost.