E. Cobham Brewer 1810–1897. Dictionary of Phrase and Fable. 1898.
Un’der-cur’rent
metaphorically means something at work which has an opposite tendency to what is visible or apparent. Thus in the Puritan supremacy there was a strong under-current of loyalty to the banished prince. Both in air and water there are frequently two currents, the upper one running in one direction, and the under one in another.
