un ‧ der ‧ cur ‧ rent /ˈʌndəˌkʌrənt $ -dərˌkɜːr-/ BrE AmE noun [countable]
1 . a feeling, especially of anger or dissatisfaction, that people do not express openly
undercurrent of
He sensed an undercurrent of resentment among the crowd.
2 . a hidden and often dangerous current of water that flows under the surface of the sea or a river