shirk - Now used almost always in the sense of avoiding doing one's rightful duty -shores, homework, military service, and the like - the word "shirk" once denoted someone whose laziness had an evil or harmful intent. A "shirk," in short, was a parasite or sponge, not a goof-off. The word, of Germanic origin, shares a root with shark - not the animal, but the person who makes a living bilking honest people out of their wages.
noon - In roman time-reckoning, developed in a sunny and temperate land, the middle of the day occurred at around what we call 3:00 p.m., roughly nine hours after sunrise. This hour was called nonus, meaning "the ninth hour" and referring to the middle of the afternoon. In our system of reckoning, "noon" now stands at the middle of the twenty-four hour day.
Q-tips - In 1923, an engineer named Leo Gerstenzang noted that his wife was cleaning their daughter's ear canal with a small ball of cotton attached to a toothpick. Afraid that the toothpick might hurt the girl, he created a rolled-paper, blunt-ended handle to which a cotton ball was glued so that it could not come off. He named the invention "Baby Gay" after his daughter but in 1926 changed the name to "Q-tips," the Q being an abbreviation for "quality."
rickety - Rickets, a skeletal disorder in infants caused by a lack of vitamin D, is seldom encountered in the United States these days. The disease, from the Greek rhachis, "spine," was once much more common, leading to this adjective, which means "being or appearing to be so unstable as to be in danger of falling at any moment."
I'll be a monkey's uncle - Now a somewhat old-fashioned exclamation of surprise, this expression barely concels the fierce battles of evolution at the time of its coinage in the early 1920s, arguments made famous by the so-called Scopes Monkey Trial of 1925. The phase also has a hint of confusion, suggesting that apes descended from humans and not, as Darwin maintained, that apes and humans had a common ancestor.
piping hot - Once a proud tagline for restaurant coffee, "piping hot" means hot enough to send steam pip-pip-pipping out of the complaining seams where metal pipes meet.
kow-tow - In premodern China, a sign of absolute subservience was to bow deeply and fall on the ground, touching one's forehead to the floor. This act came into English as "kow-tow," from the Chinese kotou, meaning "to knock one's head." Metaphorically, it now means to yield slavishly to another's demands.