rising tide is a noun meaning "the occurrence of incoming water (between a low tide and the following high tide)". It carries one recorded sense.
the occurrence of incoming water (between a low tide and the following high tide)
“a tide in the affairs of men which, taken at the flood, leads on to fortune”
Definitions, synonyms and semantic relations for rising tide come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.