WordNet (r) 3.0 (2006):

tie up
    v 1: secure with or as if with ropes; "tie down the prisoners";
         "tie up the old newspapers and bring them to the recycling
         shed" [syn: tie down, tie up, bind, truss]
    2: invest so as to make unavailable for other purposes; "All my
       money is tied up in long-term investments"
    3: restrain from moving or operating normally; "Traffic is tied
       up for miles around the bridge where the accident occurred"
    4: secure in or as if in a berth or dock; "tie up the boat"
       [syn: moor, berth, tie up]
    5: finish the last row [syn: tie up, bind off]

Moby Thesaurus II by Grady Ward, 1.0:

306 Moby Thesaurus words for "tie up":
   Anschluss, act in concert, act together, addition, affiliate,
   affiliation, afterthought, agglomeration, agglutination,
   aggregation, agreement, alight, alignment, alliance, ally,
   amalgamate, amalgamation, anchor, articulation, assimilation,
   associate, association, bale, band, band together, bandage,
   be in league, belt, bend, bind, bind up, blend, blending, block,
   blockage, bond, boycott, boycottage, brace, bracketing, bridle,
   bundle, bundle up, bureaucratic delay, cabal, cahoots, cartel,
   cast anchor, centralization, chain, cinch, clog, club together,
   clustering, coact, coadunation, coalesce, coalescence, coalition,
   collaborate, colleagueship, collegialism, collegiality, collude,
   combination, combine, combo, come to anchor, come to land,
   communication, composition, comradeship, concatenation, concert,
   concord, concourse, concur, concurrence, confederacy, confederate,
   confederation, confluence, confraternity, congeries,
   conglomeration, conjugation, conjunction, connection, consolidate,
   consolidation, conspiracy, conspire, convergence, cooperate,
   copartnership, copartnery, copulation, corner, coupling, curb,
   debark, debus, delay, delayage, delayed reaction, deplane,
   detention, detrain, disembark, disemplane, do business with, do up,
   dock, double take, dragging, drop anchor, drop the hook, ecumenism,
   embodiment, enchain, encompassment, engross, enosis, entrammel,
   fasten, federalization, federate, federation, fellowship, fetter,
   forestall, fraternalism, fraternity, fraternization, freemasonry,
   fuse, fusion, gathering, get heads together, get together, gird,
   girdle, girt, girth, go ashore, go partners, gyve, halt, hamper,
   handcuff, hang together, hang-up, harmonize, hindrance, hobble,
   hog, hog-tie, hold together, holdup, hook up, hookup, hopple,
   inclusion, incorporation, integration, intercommunication,
   intercourse, interim, interlinking, jam, job action, join, join in,
   join together, joinder, joining, jointure, junction, junta, kedge,
   kedge off, keep together, knotting, lace, lag, lagging, land, lash,
   lash and tie, lay anchor, league, league together, leash, liaison,
   linkage, linking, lockout, logjam, make a landfall,
   make common cause, make fast, make land, make port, manacle,
   marriage, meeting, meld, melding, merge, merger, merging,
   monopolize, moor, moratorium, obstruction, outlaw strike, pack,
   package, package deal, pairing, paperasserie, parcel, partner,
   partnership, pause, peg down, picket, pin down, pinion, play ball,
   pull together, put heads together, put in, put in irons,
   put into port, reach land, reciprocate, red tape, red-tapeism,
   red-tapery, reprieve, respite, restrain, retardance, retardation,
   revolt, roll up, rope, rulebook slowdown, secure, shackle, sick-in,
   sit-down, sit-down strike, slow-up, slowdown, slowness, sodality,
   solidification, sorority, splice, stand together, stay,
   stay of execution, stop, stoppage, straitjacket, strap, strike,
   suspension, swaddle, swathe, symbiosis, sympathy strike,
   syncretism, syndication, syneresis, synthesis, take it all,
   team up, tether, throw in together, tie, tie down, tie in, tie-in,
   time lag, trammel, truss, truss up, turnout, unboat, unification,
   union, unite, unite efforts, wait, walkout, wedding,
   wildcat strike, wire, work stoppage, work together, wrap, wrap up,
   yoking