一杯

1. Origins, structure, and basic meaning

• Structure: Written 一杯 and read いっぱい, it can mean one cupful or a state in which something is completely full.
• Basic usage: It is used for ordering a drink and for a bag packed to capacity.

2. Common pitfalls and similar expressions

• Quantity versus fullness
  • Context determines whether it counts one serving or describes maximum capacity.