一滴

1. Origins, structure, and basic meaning

• Structure: 一滴 (いってき) is a quantity expression counting one drop of liquid. The examples contrast an affirmative amount with emphatic negation using も.
• Basic usage: One raindrop falls from a leaf tip; not even one drop of oil remains in a bottle.

2. Common pitfalls and similar expressions

• Single drop present and even one drop denied
  • 一滴落ちた affirms the smallest unit; 一滴も…ない negates even that minimum. The second does not leave one drop.