Foreign Words & Phrases You Always Wonder About
Recently someone asked me if vis-á-vis was not a mistake in English! No it isn’t, it’s one of many foreign phrases that are commonly used. Of course clarity is the sine qua non of good writing, and the overuse of such words confuses readers. Besides, there's nothing worse than trying to impress and getting it wrong. When it comes to foreign phrases, chi non fa, non falla (he who doesn’t do, doesn’t fail)! 

ad hoc
[Latin]: for this. “Ad hoc solutions”.
ad nauseam 
[Latin]: to a sickening degree. “The politician uttered one platitude after another ad nauseam”. 
aficionado 
[Spanish]: a fan. “I was surprised at what a football aficionado she had become”. 
a priori 
[Latin]: based on theory rather than observation. “The fact that their house is in such disrepair suggests a priori that they are having financial difficulties”. 
beau monde (as in French) 
bête noire (as in French)
bona fide 
[Latin]: in good faith, genuine. “For all her reticence and modesty, it was clear that she was a bona fide expert in her field”. 
carpe diem 
[Latin]: seize the day. “So what if you have an 8:00 a.m. meeting tomorrow and a full day of appointments? Carpe diem!”. 
carte blanche (as in French) 
cause célèbre (as in French)
coup de grâce (as in French)
de rigueur (as in French)
deus ex machina 
[Latin]: a contrived device to resolve a situation. “Stretching plausibility, the movie concluded with a deus ex machina ending in which everyone was rescued at the last minute”. 
doppelgänger 
[German]: a ghostly double or counterpart of a living person. “I could not shake the sense that some shadowy doppelgänger echoed my every move”. 
enfant terrible (as in French)
ex cathedra 
[Latin]: with authority, used especially of those pronouncements of the pope that are considered infallible. “I resigned myself to obeying; my father's opinions were ex cathedra in our household”. 
fait accompli (as in French)
faux pas (as in French) 
flagrante delicto 
[Latin]: in the act. “The detective realized that without hard evidence he had no case; he would have to catch the culprit flagrante delicto”. 
hoi polloi 
[Greek]: the common people. “Marie Antoinette recommended cake to the hoi polloi”. 
in situ 
[Latin]: situated in the original or natural position. “I prefer seeing statues in situ rather than in the confines of a museum”. 
ipso facto 
[Latin]: by the fact itself. “An extremist, ipso facto, cannot become part of a coalition”. 
je ne sais quoi (as in French)
literati
[IT] the educated class.
mano a mano 
[SP]: a direct confrontation or conflict. “‘Stay out of it,’ he admonished his friends, ‘I want to handle this guy mano a mano’”. 
mea culpa 
[Latin]: I am to blame. “His mea culpa was so offhand that I hardly think he meant it”. 
modus operandi 
[Latin]: a method of operating. “Her modus operandi is to sugarcoat the truth so thoroughly that the news almost seems welcome”. 
ne plus ultra 
[Latin]: the highest degree of a quality or state. “Pulling it from the box, he realised he was face to face with the ne plus ultra of computers”. 
nom de guerre (as in French)
nom de plume (as in French)
persona non grata 
[Latin]: unacceptable or unwelcome person. “Once I was cut out of the will, I became persona non grata among my relatives”. 
pro bono 
[Latin]: done or donated without charge; free. “The lawyer's pro bono work gave him a sense of value”. 
quid pro quo 
[Latin]: something for something; an equal exchange. “She vowed that when she had the means, she would return his favours quid pro quo”.
sine qua non 
[Latin]: indispensable. “Lemon is the sine qua non of this recipe”. 
verboten 
[German]: prohibited. “That topic, I am afraid, is verboten in this household”. 
zeitgeist 
[German]: the spirit of the time; general trend of thought or feeling characteristic of a particular period of time. “She blamed it on the zeitgeist, which encouraged hedonistic excess”.