An embargo is, at root, a bar across a door. The word has kept that picture for more than four centuries.
English borrowed it from Spanish in the 1590s, according to Etymonline. In Spanish, embargo meant "seizure, arrest," and it was the noun of the verb embargar, "to restrain, impede, arrest." Behind the Spanish verb sits a reconstructed Vulgar Latin verb, imbarricare. It joins in-, "into, upon," to barra, "bar." The same barra gave English the noun bar, first a stake or rod of iron used to fasten a door or gate.
The first English sense was narrow and maritime. Etymonline defines it as an order forbidding ships of certain other nations from entering or leaving a nation's ports. The verb, to embargo a ship or a cargo, followed in the 1640s. Today the noun covers official restrictions on trade well beyond ships and ports.
The most famous American embargo shows how literal the word could be. In 1807, at the request of Thomas Jefferson, Congress passed the Embargo Act. According to NCpedia, it meant American ships could not carry cargo to foreign ports, and foreign ships could not load cargo in American ports. It was aimed at Britain, and it hurt American trade badly. Joseph Story, then in Congress, wrote that it "prostrated the whole commerce of America."
Opponents attacked it with wordplay. An 1807 cartoon showed a snapping turtle named Ograbme seizing a merchant. Ograbme is "embargo" spelled backward, and read aloud it says "O, grab me."
The same Latin bar runs through embarrass. Etymonline traces it to French embarrasser, literally "to block," from Italian imbarrare, "to bar." To embarrass someone was first to perplex them, by the 1680s to hamper or hinder them, and only by 1809 to make them feel awkward.
One word that looks like it belongs to the family probably does not. Barricade is sometimes linked to the same bar. Etymonline traces it instead to Spanish barricada, "made of barrels," from barrica, "barrel," a word of unknown origin. As far as the record shows, a barricade was built from casks, not bars.