Can you categorise terms that use two related but possibly contrasting words together, to describe something like a totality?
Two examples I can think of:
"I searched far and wide" - meaning, you searched everywhere.
"I looked high and low" - meaning, again, you looked everywhere.
In both cases, the independent terms don't literally contribute to the final meaning, but you're putting these two terms together to make them more than the sum of their parts.