“a square meal”中的“square”和“正方形”壓根兒沒啥關系，在柯林斯字典中，“square”有壹條釋義是“satisfying；solid；substantial”，也就是“令人滿足的；實在的；大量的”意思。所以，這個表達指的是“壹頓飽飯”，指吃的東西豐盛得不得了。
造個句，“During this week's training, we haven’t had a square meal.”就是“在這周訓練期間，我們沒吃上壹頓飽飯”的意思。
相關短語：
meal plan 膳食計劃
box meal 盒飯?
meal pal 飯友，飯搭子（壹種稱呼。是壹種用在經常在壹起吃飯的人之間的，故名飯友。）?
meal allowance 餐貼?
prepare a meal 做飯?
main meal 主餐?
eat a meal 吃飯?
a value meal 超值套餐?
good meal 好飯菜?
a hearty meal 豐盛的壹餐?
例句：
1.I eat three square meals a day.?
2.We haven't had a square meal for a week.?
3.This is the first square meal I've had in days.?
4.Eat three square meals a day and think of nothing else&be well fed and care about nothing else.?
中文：1.我壹日三頓飯吃得很豐盛。 2.壹周來我們沒有吃過壹頓正經飯。 3.這是我幾天來吃得最好的壹餐。 4.飽食終日,無所用心。