'Undertide' definitions:

Definition of 'undertide'

From: WordNet
noun
A current below the surface of a fluid [syn: undertide, undercurrent]

Definition of 'Undertide'

From: GCIDE
  • Undertide \Un"der*tide`\, Undertime \Un"der*time`\, n. [Under + tide, time. Cf. Undern.] The under or after part of the day; undermeal; evening. [Obs.] [1913 Webster]
  • He, coming home at undertime, there found The fairest creature that he ever saw. --Spenser. [1913 Webster]