The Collaborative International Dictionary of English v.0.48:

Embargo \Em*bar"go\, v. t. [imp. & p. p. Embargoed; p. pr. &
   vb. n. Embargoing.]
   To lay an embargo on and thus detain; to prohibit from
   leaving port; -- said of ships, also of commerce and goods.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Embargo \Em*bar"go\, n.; pl. Embargoes. [Sp., fr. embargar to
   arrest, restrain; pref. em- (L. in) + Sp. barra bar, akin to
   F. barre bar. See Bar.]
   An edict or order of the government prohibiting the departure
   of ships of commerce from some or all of the ports within its
   dominions; a prohibition to sail.
   [1913 Webster]

   Note: If the embargo is laid on an enemy's ships, it is
         called a hostile embargo; if on the ships belonging to
         citizens of the embargoing state, it is called a civil
         embargo.
         [1913 Webster]

WordNet (r) 3.0 (2006):

embargo
    n 1: a government order imposing a trade barrier [syn:
         embargo, trade embargo, trade stoppage]
    v 1: ban the publication of (documents), as for security or
         copyright reasons; "embargoed publications"
    2: prevent commerce; "The U.S. embargoes Libya"

Moby Thesaurus II by Grady Ward, 1.0:

106 Moby Thesaurus words for "embargo":
   Eighteenth Amendment, Prohibition Party, Volstead Act, ban, bar,
   bar out, barrier, barring, block, blockade, blockage, boycott,
   cease, cessation, check, circumscription, contraband, count out,
   cut off, debar, debarment, debarring, demarcation, denial, deny,
   disallow, disallowance, enjoin, exception, exclude, exclude from,
   exclusion, forbid, forbiddance, forbidden fruit, forbidding,
   freeze out, hinder, hindrance, hold back, hold up, ignore, impede,
   impediment, inadmissibility, index, index expurgatorius,
   index librorum prohibitorum, inhibit, inhibition, injunction,
   interdict, interdiction, interdictum, keep out, law, leave out,
   lock out, lockout, narrowing, no-no, nonadmission, omission, omit,
   ostracize, outlaw, pass over, preclude, preclusion, prevent,
   prevention, prohibit, prohibition, prohibitory injunction,
   proscribe, proscription, refusal, refuse, reject, rejection,
   relegate, relegation, repress, repression, repudiate, repudiation,
   restrain, restraint, restrict, restriction, restrictive covenants,
   retard, rule out, ruling out, say no to, send to Coventry,
   shut out, statute, stop, stoppage, sumptuary laws, suppress,
   suppression, taboo, zoning, zoning laws



Bouvier's Law Dictionary, Revised 6th Ed (1856):

EMBARGO, maritime law. A proclamation, or order of state, usually issued in
time of war, or threatened hostilities, prohibiting the departure of ships
or goods from some, or all the ports of such state, until further order. 2
Wheat. 148.
     2. The detention of ships by an embargo is such an injury to the owner
as to entitle him to recover on a policy of insurance against "arrests or
detainments." And whether the embargo be legally or illegally laid, the
injury to the owner is the same; and the insurer is equally liable for the
loss occasioned by it. Marsh. Ins. B. 1, c. 12, s. 5; 1 Kent, Com. 60 1
Bell's Com. 517, 5th ed.
     3. An embargo detaining a vessel at the port of departure, or in the
course of the voyage, does not, of itself, work a dissolution of a charter
party, or the contract with the seamen. It is only a temporary restraint
imposed by authority for legitimate political purposes, which suspends, for
a time, the performance of such contracts, and leaves the rights of parties
untouched, 1 Bell's Com. 517; 8 T. R. 259; 5 Johns. R. 308; 7 Mass. R. 325,
3 B. & P. 405-434; 4 East, R. 546-566.