fritillaries (pg. 52) -- Well, it's a kind of plant. That's what I get from wikipedia.
Lammas (pg. 52) -- August 1st is Lammas Day, a festival of the wheat harvest.
distraints (pg. 53) -- The legal right of a landlord to obtain a court order and seize tenants'possessions to pay for back rent.
euphroes (pg. 234) -- A suspended batten or plate of wood or brass pierced with holes through which the cords of a crowfoot are rove to suspend an awning.
Clarissa Harlowe (pg. 164) -- The heroine of one of Richardson's novels, exhibiting a female character which, as described by him, is pronounced to be "one of the brightest triumphs in the whole range of imaginative literature," is described by Stopford Brooke "as the pure and ideal star of womanhood." Interesttingly, the famous nurse Clara Barton's real name is Clarissa Harlowe Barton.
vitiated air (pg. 267) -- To reduce the value or impair the quality of.
"What's the buzz, Bob?" -- (pg. 157)
...and she had read right through Clarissa Harlowe without hanging herself (although that was sometimes only for want of a convenient hook)... -- (pg. 164)
the ladies of the town had sequi me (pg. 107) -- "Follow me"
madder (pg. 149) -- A red dye made from Rubia tinctorum.
spirketing (pg. 204) -- The planking from the waterways up to the port sills.
ultima Thule (pg. 269) -- A distant unknown region; the extreme limit of travel and discovery.
Heautontimoroumenos (pg. 283) -- The title of a Latin play by Terence, an adaptation of an earlier Greek work.
Batavia (pg. 327) -- The name of Jakarta, Indonesia (formerly Dutch East Indies) during the colonial period.
...ast illi solvuntur frigore membra... (pg. 384) -- But the other's limbs are benumbed by cold, and injured life with a groan flees beneath the shadows.
creta alba (pg. 229) -- Chalk or calcium carbonate. There's a web site for this stuff at Master and Commander medical terms
barca-Longa (pg. 253) -- A two or three-masted lugger found on the coasts of Spain and Portugal as well as more widely in the Mediterranean Sea. And here I thought it was some kind of reclining chair!
membrum virile (pg. 345) -- Uh, penis.
squills (pg. 348) -- Sea squill is a bulb which sends up a tall stalk topped by an inflorescence of small white flowers, followed by a rosette of large dull green leaves, that last until the following summer. The bulb can get quite large, reaching over five pounds in weight.
to lie in such a dismal plash (pg. 176) -- A heavy rain.
No Gretna Green (pg. 199) -- A village in Scottland where many eloping couples are married.
coxcombery (pg. 300) -- Behavior that is characteristic of a coxcomb : foppery.
fanfaronade (pg. 300) -- Empty boasting.
sharks are mostly gammon (pg. 300) -- Misleading or nonsensical talk; humbug.
an unrivalled cholagogue (pg. 332) -- A cholagogue is a medicinal agent which promotes the discharge of bile from the system, purging it downward..
...a thunderous, long, long fart.
"I beg your pardon," said the midshipman in the silence.
"Oh, that's all right," said Diana coldly. "I thought it was the horse." -- pg. 46
Quo me rapis (pg. 52) -- Interpetations abound. From Horace, "where are you carrying me off to?"
deodands (pg. 52) -- An object or instrument which becomes forfeit because it has caused a person's death.
empiric (pg. 54) -- One who is guided by practical experience rather than precepts or theory, or, an unqualified or dishonest practitioner; a charlatan. Well, that clears it up!
Cadmus (pg. 66) -- When he sowed the dragon's teeth armed men sprang up.
portable soup (pg. 66) -- A precursor to boullion.
she was in kindle (pg. 222) -- To give birth to young.
Marquesas (pg. 235) -- Islands in French Polynesia.
volto sciolto pensieri stretti (pg. 249) -- Open face, concealed thoughts.
il faut souffrir pour être beau (pg. 298) -- One must suffer in order to be beautiful.
Old Sodbury's Island (pg. 330) -- Fictional island.
Juan Fernández (pg. 351) -- Island chain off the coast of Chile.
titivated (pg. 42) -- To make decorative additions to; spruce up.
drabogues (pg.224) -- Slut, whores, trollops.
hussif (pg. 234) -- Case for needles, thread etc.
vinolent (pg. 252) -- Given to wine; drunken; intemperate.
kevel (pg. 272) -- A strong bitt, cleat, or bollard for securing heavy hawsers.
barge-pole (pg. 18) -- A long pole used to propel or guide a barge. Also called a quant pole.
Jew-man from Mogador (pg. 85) -- Portuguese name for city of Essaouira in Morroco. What's this got to do with birds? I don't know.
puddings (pg. 76) -- Puddening: A quantity of rope-yarn, or the like, placed, as a fender, on the bow of a boat, or, a bunch of soft material to prevent chafing between spars, or the like. Also called pudding.
pinnace (pg. 87) -- Small boat, could be rowed or sailed.
Bonhomme Richard (pg. 280) -- Can't be John Paul Jones' ship, that was sunk in 1779. Maybe a fictional "what if it wasn't sunk" scenario.
struck down by a levinflash (pg. 302) -- Lightning flash. "Levin" is an archaic term for lightning, from Middle English.
weather-helm (pg. 306) -- The tendency of a sailing vessel to turn up into the wind. In general having a slight weather helm is considered a good characteristic since it gives the boat tight steering and stops the vessel when the helm is left untended.
hartshorn (pg. 329) -- An aqueous ammonia solution used as smelling salts, formerly prepared from the horns of deer.
fearnought screens (pg. 355) -- A covering for the hatches of thick felt. moistened with water.
Shiver the foretopsail (pg. 357) -- To cause (a sail) to flutter by sailing too close to the wind.
For me tobacco is the crown of the meal, the best opening to a day, a great enhancer of the quality of life. (pg. 212)
Papin's digester (pg. 610) -- A high-pressure cooker, precursor to the domestic pressure cooker.
beck (pg. 109) -- A gesture requesting attention, such as a nod or wave.
"...otherwise it [laudanum] is no more injurious than smoking tobacco." (pg. 56)
plum-duff (pg. 193) -- A stiff flour pudding steamed or boiled usually and containing e.g. currants and raisins and citron.
red Constantia and a drowned baby (pg. 327) -- A type of suet pudding, if you can imagine!
young Stupor Mundi (pg. 334) -- The wonder of the world, referring to Jack's new son.
widow's cruse (pg. 46) -- An endless or unfailing source of supply. [allusion to I Kings 17:16].
âge ingrat (pg. 93) -- Adolenscence.
nacreous flesh (pg. 06) -- Resembling nacre; lustrous; pearly.
marthambles (pg. 132) -- Research seems to say that O'Brian got the word from an old pamphlet or poster, but the disease is not real.
galley-ranger (pg. 132) -- An unpopular man who is forced to mess by himself having been turned away from all of the messes in a ship.
vails (pg. 263) -- Take off one's hat or otherwise show respect or submission to someone.
Oh what a glorious name for a tight, sweet, newly-coppered, broad-buttocked little ship, a solace to any man's heart. (pg. 80)
Honi soit qui mal y pense (pg. 48) -- Shamed be he who thinks evil of it.
lucas a non lucendo (pg. 180) -- Literally, "[called] a grove for being unlit", but used as "a contradiction in terms, often with facetious intent", used here in comment on the rose garden with no roses.
quasi pannus menstruat (pg. 241) -- "Like a menstrual cloth", is probably referring to Ezekiel 36:17, likening human justice to a woman's unclean rag.