meaning of undercurrent
1. A current below the surface of water, sometimes flowing in a contrary direction to that on the surface.
2. Hence, figuratively, a tendency of feeling, opinion, or the like, in a direction contrary to what is publicly shown; an unseen influence or tendency; as, a strong undercurrent of sentiment in favor of a prisoner.
3. Running beneath the surface; hidden.
4. subdued emotional quality underlying an utterance; implicit meaning