The tablespoon is a unit of volume in the US customary system and uses the symbol Tbsp.
In the kitchen, the tablespoon is the larger of the commonly used spoons served at the table and represents 1/2 US fluid ounce or, expressed in SI / metric format; 14.78676 ml.
This is often expressed as equivalent to 3 teaspoons (3 Tsp) although strictly speaking it is a little under the size of 3 metric teaspoons (5 ml) at 4.92892159375 ml. It was established to assist normal kitchens with recipes without the need for specific measuring equipment or devices. Although many spoons differ in sizes (and very rarely is a spoon filled accurately) it allowed for a decent "catch-all" and gave a "good enough" result most of the time.
The bushel is a unit of volume in the imperial unit system with the symbol bsh.
1 bushel is equal to 8 dry gallons, or 36.36872 litres.
The bushel was introduced in England as a unit to bridge the relatively large gap between a pound and a ton - and was used largely to measure volumes of liquid being imported and exported following the Norman Conquest such as wine and ale.
The name bushel comes from the ancient French 'boissiel' which means 'little box'.