Meaning of UNDERCURRENT in English

UNDERCURRENT

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

Longman Dictionary of Contemporary English.      Longman - Словарь современного английского языка.