Instead, "under the weather" is a saying with a nautical background. Sailors and passengers on ships would get ill or seasick during their journey. Sick passengers were ordered to go below deck, which was believed to be the most stable part of the ship as well as a shelter from the weather. This was to ensure a speedy recovery from whatever was ailing them.
"[A passenger would] be protected from the elements -- literally 'under the weather' -- and this became a synonym for being ill," McFedries pointed out.
This is a tricky one. Silver is known to have antimicrobial properties that can ward off bacteria and viruses. But whether the old adage "born with a silver spoon in your mouth" is related to this scientific fact is debatable.
In medieval tradition, wealthy godparents gave their grandchildren silver spoons as gifts during at their christening ceremonies. Because only the rich could afford such items, silver spoons became a symbol of the affluent.
"The elite class already had silver," said Albert Jack, historian and author of "Red Herrings and White Elephants: The Origins of the Phrases We Use Everyday." Since the upper class of society had silver among their troves of treasures, those born into that class were seen as "born with a silver spoon in their mouths."
The phrase has appeared in several pieces of literature, including Cervantes' "Don Quixote." It made its first appearance in American language in the "Adams Family Correspondence," a collection of letters exchanged between John and Abigail Adams.
The connection to colds and flu or just being sick in general is unclear. Some definitions of the phrase state that because children fed with silver spoons were observed to get sick less often as opposed to the poor class, "born with a silver spoon in your mouth" has a medical origin.
Phrase experts are skeptical of this assertion.
"This means 'born into a wealthy family,'" McFedries said. "So it doesn't have anything to do with colds, flu or illness."
"Sick as a dog" is a familiar phrase uttered among us to refer to someone who is battling a nasty cold or flu. But why is man's best friend included in the phrase?
Across the pond in London, they use "sick as a parrot" instead to deliver the notion that someone is really sick. As with "under the weather," "sick as a parrot" also has a nautical history.
"Parrots [were carried] onboard sailing ships," historian Jack said, adding that sailors would take them along long trips across oceans.
Among the supply of food on the ship was raw fruit that would easily spoil. The rotted fruits was given to the parrots to eat.
"[The juice of] the raw fruit would turn to alcohol," Jack said. "The parrots would consume the fermenting fruit," which led to some unfortunate consequences.
In reaction to eating the spoiled loot, the parrots would get sick and woozy and start throwing up, much like the reaction from drinking one too many.
The symptoms of digesting these rotted items were seen to be very similar to those from stomach flu, hence the phrase "sick as parrot."
When the phrase was transported to America, it morphed into "sick as a dog," not referring to someone with a cold or flu, but the nauseous reaction one gets after eating something unagreeable to the stomach.