Source : Webster's Revised Unabridged Dictionary (1913)

Undermeal \Un"der*meal`\, n. [AS. under under + m?l part or
   portion; cf. AS. underm?l midday. See {Under}, {Meal} a part,
   and cf. {Undern}.]
   1. The inferior, or after, part of the day; the afternoon.
      [Obs. or Prov. Eng.]

            In undermeals and in mornings.        --Chaucer.

   2. Hence, something occurring or done in the afternoon; esp.,
      an afternoon meal; supper; also, an afternoon nap; a
      siesta. [Obs. or Prov. Eng.]

            Another great supper, or undermeal, was made ready
            for them, coming home from ditching and plowing.
                                                  --Withals
                                                  (1608).

            I think I am furnished with Cattern [Catharine]
            pears for one undermeal.              --B. Jonson.

            In a narrower limit than the forty years' undermeal
            of the seven sleepers.                --Nash.