The Collaborative International Dictionary of English v.0.48:

Attach \At*tach"\, n.
   An attachment. [Obs.] --Pope.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Attach \At*tach"\, v. t. [imp. & p. p. Attached; p. pr. & vb.
   n. Attaching.] [OF. atachier, F. attacher, to tie or
   fasten: cf. Celt. tac, tach, nail, E. tack a small nail, tack
   to fasten. Cf. Attack, and see Tack.]
   1. To bind, fasten, tie, or connect; to make fast or join;
      as, to attach one thing to another by a string, by glue,
      or the like.
      [1913 Webster]

            The shoulder blade is . . . attached only to the
            muscles.                              --Paley.
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            A huge stone to which the cable was attached.
                                                  --Macaulay.
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   2. To connect; to place so as to belong; to assign by
      authority; to appoint; as, an officer is attached to a
      certain regiment, company, or ship.
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   3. To win the heart of; to connect by ties of love or
      self-interest; to attract; to fasten or bind by moral
      influence; -- with to; as, attached to a friend; attaching
      others to us by wealth or flattery.
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            Incapable of attaching a sensible man. --Miss
                                                  Austen.
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            God . . . by various ties attaches man to man.
                                                  --Cowper.
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   4. To connect, in a figurative sense; to ascribe or
      attribute; to affix; -- with to; as, to attach great
      importance to a particular circumstance.
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            Top this treasure a curse is attached. --Bayard
                                                  Taylor.
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   5. To take, seize, or lay hold of. [Obs.] --Shak.
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   6. To take by legal authority:
      (a) To arrest by writ, and bring before a court, as to
          answer for a debt, or a contempt; -- applied to a
          taking of the person by a civil process; being now
          rarely used for the arrest of a criminal.
      (b) To seize or take (goods or real estate) by virtue of a
          writ or precept to hold the same to satisfy a judgment
          which may be rendered in the suit. See Attachment,
          4.
          [1913 Webster]

                The earl marshal attached Gloucester for high
                treason.                          --Miss Yonge.
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   Attached column (Arch.), a column engaged in a wall, so
      that only a part of its circumference projects from it.
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   Syn: To affix; bind; tie; fasten; connect; conjoin; subjoin;
        annex; append; win; gain over; conciliate.
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The Collaborative International Dictionary of English v.0.48:

Attach \At*tach"\, v. i.
   1. To adhere; to be attached.
      [1913 Webster]

            The great interest which attaches to the mere
            knowledge of these facts cannot be doubted.
                                                  --Brougham.
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   2. To come into legal operation in connection with anything;
      to vest; as, dower will attach. --Cooley.
      [1913 Webster]

WordNet (r) 3.0 (2006):

attach
    v 1: cause to be attached [ant: detach]
    2: be attached; be in contact with
    3: become attached; "The spider's thread attached to the window
       sill" [ant: come away, come off, detach]
    4: create social or emotional ties; "The grandparents want to
       bond with the child" [syn: bind, tie, attach, bond]
    5: take temporary possession of as a security, by legal
       authority; "The FBI seized the drugs"; "The customs agents
       impounded the illegal shipment"; "The police confiscated the
       stolen artwork" [syn: impound, attach, sequester,
       confiscate, seize]

Moby Thesaurus II by Grady Ward, 1.0:

106 Moby Thesaurus words for "attach":
   add, adhere, adjoin, affiliate, affix, agglutinate, anchor, annex,
   append, apply, appropriate, ascribe, assign, associate, attract,
   attribute, belay, bend, bind, bond, braze, burden, cement, cinch,
   clamp, cleave, clinch, collectivize, commandeer, communalize,
   communize, complicate, confiscate, conjoin, connect, cramp,
   decorate, distrain, encumber, endear, engraft, enlist, expropriate,
   fasten, fix, garnish, give, glue, glue on, graft, grapple,
   hitch on, impound, impress, impute, infix, join, join with, knit,
   lay hold of, levy, make fast, moor, nationalize, ornament,
   paste on, pin, place, plus, postfix, prefix, press, put, put to,
   put with, refer, replevin, replevy, rivet, saddle with, screw up,
   second, secure, seize, sequester, sequestrate, set, set to,
   slap on, socialize, solder, stick, subjoin, suffix, superadd,
   superpose, tack on, tag, tag on, tie, tighten, trice up, trim,
   unite, unite with, weld