The Collaborative International Dictionary of English v.0.48:

Delve \Delve\v. t. [imp. & p. p. Delved; p. pr. & vb. n.
   Delving.] [AS. delfan to dig; akin to OS. bidelban to bury,
   D. delven to dig, MHG. telben, and possibly to E. dale. Cf.
   Delf a mine.]
   1. To dig; to open (the ground) as with a spade.
      [1913 Webster]

            Delve of convenient depth your thrashing floor.
                                                  --Dryden.
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   2. To dig into; to penetrate; to trace out; to fathom.
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            I can not delve him to the root.      --Shak.
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The Collaborative International Dictionary of English v.0.48:

Delve \Delve\, v. i.
   To dig or labor with a spade, or as with a spade; to labor as
   a drudge.
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         Delve may I not: I shame to beg.         --Wyclif (Luke
                                                  xvi. 3).
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The Collaborative International Dictionary of English v.0.48:

Delve \Delve\, n. [See Delve, v. t., and cf. Delf a mine.]
   A place dug; a pit; a ditch; a den; a cave.
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         Which to that shady delve him brought at last.
   --Spenser.
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         The very tigers from their delves
         Look out.                                --Moore.
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The Collaborative International Dictionary of English v.0.48:

Delf \Delf\ (d[e^]lf), n. [AS. delf a delving, digging. See
   Delve.]
   A mine; a quarry; a pit dug; a ditch. [Written also delft,
   and delve.] [Obs.]
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         The delfts would be so flown with waters, that no gins
         or machines could . . . keep them dry.   --Ray.
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WordNet (r) 3.0 (2006):

delve
    v 1: turn up, loosen, or remove earth; "Dig we must"; "turn over
         the soil for aeration" [syn: dig, delve, cut into,
         turn over]

Moby Thesaurus II by Grady Ward, 1.0:

76 Moby Thesaurus words for "delve":
   backset, beat the bushes, bore, burrow, cavity, cultivate, culture,
   cut, dig, dig out, dike, dredge, dress, drill, drive, excavate,
   explore, fallow, fertilize, forage, force, frisk, furrow,
   go through, gouge, gouge out, groove, grub, harrow, hoe, hollow,
   hunt, list, look around, look round, look through, lower, mine,
   mulch, nose around, plow, pocket, poke, poke around, prune, pry,
   quarry, rake, research, root, sap, scoop, scoop out, scrabble,
   scrape, scratch, search, search through, shovel, sink,
   smell around, spade, thin, thin out, till, till the soil, trench,
   trough, tunnel, vacancy, vacuity, vacuum, void, weed, weed out,
   work