A
Ahoy, Matey: Hail, fellow sailor.
Argh: The first word in any pirate’s vocabulary. This word is used to punctuate any sentence and should be liberally sprinkled throughout the dialogue.
Aye: Yes or any other affirmative reply.
Aft: Short for "after." Toward the rear of the ship.
Avast: Nautical term meaning stop what you are doing, derived/corrupted from 'hold fast'.

B
Becalmed: The state of a sailing ship when it cannot move because there is no wind.
Belay Stop that. "Belay that talk!" would mean "Shut up!"
Belaying pin: A short wooden rod to which a ship's rigging is secured. A common improvised weapon aboard a sailing ship, because they're everywhere, they're easily picked up, and they are the right size and weight to be used as clubs.
Bilge: The lowest part of the ship, bilge water is the foul, brackish sea water that would collect from seepage in this area.
Black Jack: A leather tankard, made stiff with a coating of tar, used by dockside pubs and taverns to serve wine and beer.
Black Spot: To "place the Black Spot" on another pirate is to sentence him to death, to warn him he is marked for death, or sometimes just to accuse him of a serious crime before other pirates.
Bosun Boatswain: a petty officer.
Bowsprit: a long spar that projected from the ship's prow.
Brethren of the Coast: The Caribbean buccaneers called themselves by this name in the 1640-1680 period. During this time, they actually formed a sort of fraternity, and did not (usually) fight each other or even steal from each other. After 1680, a new generation of pirates appeared, who did not trust each other . . . with good reason.
Blow the man down: To kill someone.
Booty: Goods obtained illegally.
Bounty: Reward or payment, usually from a government, for the capture of a criminal.
Bow: The front of the ship.
Broadside: All the guns on one side of a ship, also shots fired by that line of guns.
Bring ‘er alongside: Command to bring ships side to side for boarding.
Buccaneer: early entrepreneurs who dried the meat from wild cattle and hogs on the island of Hispañola in the early 1600's to sell to ships returning to Europe (primarily Spain). A pirate or unscrupulous adventurer.

C
Careening: Turning a ship on its side so that it can be cleaned; making the ship faster in the water - or repaired. During careening all weapons are brought ashore and the ship and pirates are vulneralble.
Cat-of-nine-tails: A type of whip often used by captains to punish and enforce his authority.
Chain Shot: Two cannonballs chained together and aimed high to destroy masts and rigging.
Corsair: maybe derived from the island name Corsica, pirate or pirate ship, esp. of Barbary (N. Africa in olden times), attacking ships of European countries; also, a French privateer, or Knights of Malta fighting the Barbary pirates.
Careen: Cleaning a ship's hull of barnacles, seaweed and marine worms by beaching it and leaning it over to one side.
Chantey: A sailor's song. Also spelled "shantey" or "shanty."
Chase: The ship being pursued. "The chase is making full sail, sir" = "The ship we're after is going as fast as she can."
Cutlass: A short, curved, thick sword, the preferred weapon of many buccaneers, possibly a carry over weapon from the days of making boucan and probably more suited to the slashing melee amidst the rigging when boarding another ship than a long sword.

D
Dance the hempen jig: To hang.
Davy Jones' locker: The bottom of the sea.
Deadlights: Eyes. "Use yer deadlights, matey!"
Dead men tell no tales: Standard pirate excuse for leaving no survivors.
Doubloon: Gold coin minted by Spain or Spanish colonies, worth about seven weeks pay for an average sailor.

E
None

F
Freebooter: Another name for a pirate or buccaneer.
Flibustier: French term for pirates during the golden age (approximately the same time the term buccaneer came into wide usage).

G
Gibbet Cage: Chains in which the corpses of pirates were hung and displayed in order to discourage piracy in others.
Gangway!: "Get out of my way!"
Gibbet: a wooden frame from which dead pirates were hung, often in a metal cage especially fitted for the pirate, as a warning to any others who would think of taking up a career of piracy
Grog: Generically, any alcoholic drink. Specifically, rum diluted with water to make it go farther.

H
Hang ‘im from the yardarm: Pirate phrase for punishment for shipmates of captured prisoners.
Hang the jib: To pout or frown.
Heave-To: To come to a halt.
Hempen Halter: The hangman’s noose.
Hornswaggle: To cheat.
Hands: The crew of a ship; sailors.
Handsomely: Quickly. "Handsomely now, men!" = "Hurry up!"
Hold: the cargo area of a ship below the main deck

I
None

J
Jolly Rodger: The pirate flag that is usually black and has an image of a skull or skeleton on it. (Each ship's was different)

K
Keelhaul: A method of punishment aboard pirate ships in which the victim was tied to the ship, thrown overboard and dragged underwater along the length of the keel.

L
Letter of Marque: License by government to attack and loot enemy ships.
Loot: Gold, money, or other goods obtained illegally.

M
Maroon: A fairly common punishment for violation of a pirate ship's articles, or offending her crew. The victim was left on a deserted coast (or, of course, an island) with little in the way of supplies. That way, no one could say that the unlucky pirate had actually been killed by his former brethren.
Mutiny: To rise against authority, particularly a naval or military power.
Me: A piratical way to say "my."
Me hearties: Typical way for a pirate leader to address his crew.
Matey: A piratical way to address someone in a cheerful, if not necessarily friendly, fashion.

N
Nelson’s Folly: Rum.
No prey, no pay: Crew received no wages, but shared in whatever loot was taken.

O
On the Account: The piratical life. A man who went "on the account" was turning pirate.

P
Pirate: Derived from the Greek pirate, meaning one who plunders on the sea.
Plunder: The act of pillaging or robbery.
Port: When facing the bow (forward), the left side of the ship. Also called Larboard.
Privateers: Government sanctioned pirates, with permission in the form of a letter of marque.
Picaroon: term meaning both pirate and slaver.
Piece of Eight: Spanish silver coin, or old Spanish peso, often cut into pieces to make change.
Ponton: An English prison hulk, or converted ship hull, where captured pirates were held.

Q
Quarter: Mercy given to those defeated.

R
Red Ensign: The British flag.
Run a rig: To play a trick.

S
Savvy: A pirate term meaning "yes" or if used in a question could mean "do you agree"
Scallywag: A villainous or mischievous person.
Scourge of the seven seas: An extremely evil pirate.
Scuttle: To sink.
Scurvy: A disease resulting from a vitamin C deficiency, characterized by weakness, anemia and spongy gums, although in the sense of 'scurvy dog' it meant low or mean (not angry, but low in quality)
Shiver me timbers: Phrase expressing surprise.
Six Pounders: Cannons.
Starboard: When facing the bow (forward), the right side of the ship.
Sea rover: Pirate; pirate's ship.
Swab: A disrespectful term for a seaman. "Man that gun, ye cowardly swabs!"

T
None

U
None

V
None

W
Walk the plank: A piratical execution. The victim, usually blindfolded or with bound hands or both, is forced to walk along a plank laid over the ship's side, to fall into the water below. Except this seems to be a total invention; it first appeared in 19th-century fiction, long after the great days of piracy.
Weigh anchor: To haul the anchor up; more generally, to leave port.

X
None

Y
Ye: Used in place of you.
Yo-ho-ho: A very piratical thing to say, whether it actually means anything or not.

Z
None