falcate \FAL-keyt, adjective:

curved like a scythe or sickle; hooked; falciform.

…Mario did the choreography and most of the puppet-work personally—his little S-shaped arms and falcate digits are perfect for the forward curve from body to snout of a standard big-headed political puppet…
— David Foster Wallace, Infinite Jest, 1996

The adult leaves are lanceolate, falcate, almost equally green on both sides.
— Murray Bail, Eucalyptus: A Novel, 1998

Falcate entered English in the 1800s from the Latin falcem meaning “sickle.”

phosphoresce \fos-fuh-RES, verb:

to be luminous without sensible heat, as phosphorus.

Maybe it’s the gloomy dark, the phosphoresce from the glubbing aquarium. But mostly it’s the way Coach’s eyes seem to vibrate when she looks at me, pupils like nail heads.
— Megan Abbott, Dare Me, 2012

From the boulevard they turned towards the pavilion, and for a long time gazed at the phosphorescent sea. Von Koren began to explain what made it phosphoresce.
— Anton Chekhov, The Duel, 1891

Phosphoresce came to English in the late-1700s from the Greek Phosphoros meaning “morning star,” or literally “torchbearer.”

mishpocha \mish-PAW-khuh, -POOKH-uh, noun:

an entire family network comprising relatives by blood and marriage and sometimes including close friends; clan.

Levinsky told him he didn’t need a lawyer. “Dealing with us is like mishpocha. Who needs a lawyer to talk tomishpocha.” Simon learned later they had cheated him, but who cares, who would have cared?
— Arthur A. Cohen, In the Days of Simon Stern, 1973

“You can speak now. We’re all mishpocha here and we got no secrets.”
— Leon Uris, Exodus, 1958

Mishpocha entered English in the mid-1800s and comes from the Yiddish and Hebrew words for “family” or “clan.”

palinode \PAL-un-nohd, noun:

1. a poem in which the poet retracts something said in an earlier poem.
2. a recantation.

He writes albas for both sexes, and in the Sonnets repents of his love poetry, writing his palinode, in true medieval fashion.
— C. S. Lewis, “Donne and Love Poetry,” Selected Literary Essays, 1969

“I shall trim their jackets for them, Mrs. Dods, if you can but bring tight evidence of the facts — I will soon bring them to fine and palinode — I will make them repent meddling with your good name.”
— Sir Walter Scott, St. Ronan’s Well, 1823

Palinode entered English in the 1600s, and comes from the Greek palinoidia meaning “poetic retraction.” It shares the root palinwith the word palindrome.

diglossia \dahy-GLOS-ee-uh, -GLAW-see-uh, noun:

1. the widespread existence within a society of sharply divergent formal and informal varieties of a language each used in different social contexts or for performing different functions, as the existence of Katharevusa and Demotic in modern Greece.
2. Pathology. the presence of two tongues or of a single tongue divided into two parts by a cleft.

Arabic took over many of the functions of Aramaic as the language of scholarship, and, as one vernacular replaced another, the original state of diglossia was restored.
— David Biale, Cultures of the the Jews: A New History, 2002

Sociolinguistic studies indicate that diglossia and code-switching are very pertinent characteristics of the linguistic repertoires of a large portion of the population…
— Christa Van der Walt, Living Through Languages: An African Tribute to René Dirven, 2006

Diglossia comes from the Greek term meaning “bilingual” and entered English in the 1950s.

xanthic \ZAN-thik, adjective:

1. of or pertaining to a yellow or yellowish color.
2. Chemistry. of or derived from xanthine or xanthic acid.

Is this stuff air that permits you to suffocate still, almost audibly at times, it’s possible, a kind of air. What exactly is going on, exactly, ah old xanthic laugh, no, farewell mirth, good riddance, it was never droll.
— Samuel Beckett, “Texts for Nothing,” Stories and Texts for Nothing, 1950-1952

I’d seen it, this time, from the end of my row, xanthic, luminous. I stood above it, my hands on my hips like an outraged housewife confronted with an unexpected mess.
— Erica Wagner, Gravity, 1997

Xanthic entered English in the 1800s from the Greek term xanthos meaning “yellow.”

sward \swawrd, noun:

1. the grassy surface of land; turf.
2. a stretch of turf; a growth of grass.

verb:
1. to cover with sward or turf.
2. to become covered with sward.

One fair half-day in the July of 1800, by good luck, he was employed, partly out of charity, by one of the keepers, to trim the sward in an oval enclosure within St. James’ Park…
— Herman Melville, Israel Potter, 1855

The arching trees gave no cover, so Edward skidded into the woodland behind the tall guardian beeches on the other side of the grove and fell down, promptly into the long grass near to the edge of the sward…
— Iris Murdoch, The Good Apprentice, 1985

Sward comes from the Proto-Germanic root swarthu- meaning “skin” or “rind.” While in Old English sward referred to the skin of an animal, by the 1400s it started referring to the outer layer of the earth where grass grows.

spelunk \spi-LUHNGK, verb:

to explore caves, especially as a hobby.

They were flown to Lebanon to ski the unlikely snow, sail the Mediterranean, spelunk the Jeita cave.
— Kim Barnes, In the Kingdom of Men. 2012

The pair of young German professors spelunking with their electric torches in the rafters of the Old-New Synagogue, or Altneuschul, had, as it happened, gone away disappointed; for the attic under the stair-stepped gables of the old Gothic synagogue was a cenotaph.
— Michael Chabon, The Amazing Adventures of Kavalier & Clay, 2000

Spelunk entered English in the 1300s from the Latin spelunca meaning “cave” or “cavern.”

codger \KOJ-er, noun:

an eccentric man, especially one who is old.

He’ll find one of those joints and be there, evening after evening, talking to the bartender confidentially but loud enough. It won’t be long before they get used to him. An old codger with money, stooped but still pretty big.
— Louis Begley, Schmidt Delivered, 2000

One of the lesser Shadows whom we shall call Baron A. had a father-in-law called Baron B., a harmless old codger long retired from the civil service and quite incapable of understanding certain Renaissance aspects of the new regime.
— Vladimir Nabokov, Pale Fire, 1962

Codger is likely related to the word cadge meaning “to beg.” Its etymology is uncertain.

wonk \wongk, noun:

1. a stupid, boring, or unattractive person.
2. a student who spends much time studying and has little or no social life; grind.
3. a person who studies a subject or issue in an excessively assiduous and thorough manner: a policy wonk.

“This is a guy who has been a policy wonk for his adult life, not only interested in what’s going on but really keeping up with it—and he’s smart as hell.”
— John Colapinto, “Enter Laughing: Senator Franken’s long journey,” The New Yorker, 2009

…Nick…found himself…running up the staris of the Capitol in pursuit of the senator’s chief aide, a gangly wonk in glasses…
— Karen Olsson, Waterloo: A Novel, 2006

The origin of wonk, a word that entered English as US slang in the 1960s, is unknown, though it might be a shortening of the UK slang wonky.