余す

1. Origins, structure, and basic meaning

• Structure: 余す (あます) is a verb meaning to leave something unused or remaining, often seen in a negative idiom.
• Basic usage: In 余すところなく and 余すことなく, it means that nothing is left and the whole amount is used.

2. Common pitfalls and similar expressions

• The positive verb inside a negative idiom
  • Although 余す itself means to leave something, its なく expressions convey using or showing everything without remainder.