The Collaborative International Dictionary of English v.0.48:

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]