Tradition, I suppose. But I've seen square plates. I suppose there's no reason why you couldn't serve a square meal on a square plate if you were so inclined...

One source for the "square meal" goes back to early days of various military academies. At mealtimes, plebes or cadets were required to sit at the edge of their seats in a modified position of attention. Food could not be picked straight from the plate to the mouth as cutting corners like that was so unmilitary. You had to form a square, with your torso and lap as half of the square and the other two sides formed by lifting a forkful of food straight up from the surface of the plate until it reached the level of your mouth and then moving the fork parallel to your lap until it reached your mouth. The return trip to the plate was the exact reverse of bringing the food to your mouth...a square meal.

"Square meal" dates to 1868, although it did not become common until around 1880. It is an Americanism. It comes from the adjectival use of square to mean sturdy or substantial. There are older, related senses of the adjective square. In the 17th century, square was used to describe someone who could eat and drink copious amounts. The shape of the serving plate is not a factor.

For the sole purpose of giving you something to ponder :)

We have square plates :)

It originated from the Royal Navy practice of serving meals on square wooden plates.

For the same reasons we park on a driveway and drive on a parkway. : )

Dear Word Detective: We were having dinner when dad decided to dazzle us with his knowledge regarding a "square meal." His explanation involved the military and the way you sit in your chair eating your meal. He described forming a square with your upright rigid body then moving your arm (holding your utensil) in a square-like motion in order to get the food to your mouth. What say you? Please advise. Our food is getting cold. -- The Finneys, via the internet. What say I? I say your dad is one weird fella, although that square-like motion of the arm is apparently the official eating procedure in at least some military academies. In any case "square meal," meaning a full and complete meal, does not refer to the manner of eating, but the quality of the meal consumed. H.L. Mencken considered "square meal" a classic 18th-century American coinage, a product of what Mencken called "the American language" breaking free of English as spoken in Great Britain. Along with "square meal," Americanisms such as "buzz saw," "cold snap" and "chain gang" combined common English words in entirely new forms, building a whole new vocabulary better suited to the New World. With its "tang and color," Mencken said, "square meal" was "as distinctively American as jazz or the quick lunch." "Square" (from the Latin "quadra," meaning "four") has always carried meanings that went beyond mere geometry. Long a synonym for "solid" or "steady," "square" in the 16th century also came to mean "fair" or "complete," as in the phrase "fair and square." The distinctively American combination of "square" and "meal" was probably first used by workers, such as farmhands, whose deal with their employers included room and board. In such an arrangement, if the board offered wasn't three full, complete meals --"three squares a day" -- it wasn't a "square deal." http://www.word-detective.com/112700.html#squaremeal Always one of my favourite sources.

The phrase is of US origin. All the early citations are from America, including this, which is the earliest print reference I have found - an advertisement for the Hope and Neptune restaurant, in the California newspaper The Mountain Democrat, November 1856: "We can promise all who patronize us that they can always get a hearty welcome and 'square meal' at the 'Hope and Neptune. Oyster, chicken and game suppers prepared at short notice." William Brohaugh, in his usually reliable 'English Through the Ages', dates the saying as having entered the language in 1840, although no supporting evidence is provided