Loosening vs Lucency

No, these are not sound-alikes.  Here is the problem. 

Loosening (g.) or loosen (v)  means to loosen, to make loose, to make less tight, as in "loosen your belt after eating," or "After a hard day's work, he loosened his tie as he relaxed with his beer."

Lucency (n.) means illumination, lighting, to shine a light on.  It means clarity, transparency.  "My grandmother would roll the filo dough until it was translucent."

Here is the problem: When people do not spell correctly, there is a tendency to confuse one word for another, especially if those words are not commonly used.  Certainly, that is the case with lucency.  I am making this entry because I recently came across "he lucent his tie."  This does, indeed, sound like loosened, but the meaning is entirely different.  It is critical that our educational system concentrate its efforts on correct spelling, if for no other reason than to encourage correct communication.  The fact that schools have recently opted to allow "creative" spelling is abhorrent, and quite misguided.

Plain vs. Plane

I imagine many folks have trouble with this one.

Plain (n.) refers to a plot of land, a large, flat, almost treeless area.  For example, "The plains of Africa are becoming smaller, and the elephants roaming the savannas are becoming endangered.  In other words, plain is a land formation.  Plain also means clear (plain to see), simple (this is plain arithmetic).

Plane (n.) also means a flat, level area, but is more abstract.  For example, "Place the windows on the same plane"  and "The educational plane in the United States lags behind other developed countries."

Plural v Pleural

Plural (adj.) means several or many; it means more than one.  It is the opposite of singular.

Pleural (adj.) refers to the lungs, as in pleural sounds (breath sounds).

Fusion v. Effusion

This is one of those sound-alikes that creates trouble.

Fusion (n.) means joined together, a synthesis, union, or combination.  When a bone is broken, sometimes both sides are fused together.

Effusion (n.) means the escape of fluid from anatomical vessels, such as in rupture.

Mendacity

Wow, what a gorgeous word.  How eloquent.  How easily misunderstood and distorted.

Mendacity (n.) means deceitfulness, dishonesty, puffery, misrepresentation, disingenuousness.  I just read a wonderful article by artist and author, Jack White (http://faso.com/fineartviews/47488/mendacity) in which he specifically discusses the downside of using mendacity to sell one's art, either by exaggerating one's talents, or otherwise misrepresenting their accomplishments or the value of their art.  This type of dishonesty is rampant in our society.  Sadly, it seems even to be encouraged, as when parents praise their children for anything they do from the time they get up in the morning; every word from these parents' mouths is "I'm proud of you, Johnny."  That does not teach the child the value of perseverance, or struggle and effort; and it certainly discourages the child from developing a backbone of honesty.

Another example: "She told her husband that she was meeting a friend for dinner.  But she did not make clear that this friend was a man, as she did not want to stir up any feelings of jealousy."

Parsimonious

A glorious word presented at our meeting last night.  I'm especially fond of it.  It is an adjective, and means frugal or stingy.  Ex: "The parsimonious tactics that Warren Buffet has practiced for a lifetime have made him one of the richest men in the world."  Another example: "Americans are not known for their parsimonious spending; they are a very consumption-oriented bunch."

In both examples, parsimonious describes behavior toward finances.  It is rarely used to describe other behaviors, although not unheard of.  For example, one might be parsimonious in one's affections, but that would be a bit unorthodox a use for the word.

Caudal versus Cottle

Admittedly, few people beside physicians would have occasion to use the word Cottle, a surgical instrument, but that notwithstanding, misspellings are rampant. 

Caudal refers to the posterior, or more precisely, a posterior approach (again, a term mostly used in surgery).